Liquid consumption status detecting method, liquid container, and ink cartridge

ABSTRACT

A method of detecting a consumption status of liquid contained in a liquid container, comprising steps of: preparing a detection device having a piezoelectric element and attaching the detection device on a desired position of the liquid container so that at least a part of the detection device contacting the liquid; measuring a residual vibration of the detection device; and detecting the consumption status of the liquid contained in the liquid container on the basis of a result of the measurement of the residual vibration.

This is a continuation of application Ser. No. 10/662,397 filed Sep. 16,2003, which is a divisional of application Ser. No. 09/574,015 filed May19, 2000, which claims priority based on a Japanese patent application,H. 11-139683 filed May 20, 1999, H. 11-147538 filed May 27, 1999 and H.11-256522 filed on Sep. 10, 1999. The entire disclosures of the priorapplications, application Ser. Nos. 10/662,397 and 09/574,015 isconsidered part of the disclosure of the present application and arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid container equipped with apiezoelectric apparatus therein which detects the consumption state ofliquid inside a liquid container which houses the liquid, by means ofdetecting change of the level of the acoustic impedance, especiallydetecting the change of the resonant frequency. More particularly, thepresent invention relates to the ink cartridge for use with an ink-jetrecording apparatus which performs the printing operation by dischargingink droplets from a nozzle opening, in a manner such that ink in apressure generating chamber is compressed by a pressure generating meanscorresponding to printing data.

2. Description of the Related Art

An ink cartridge mounted on an ink-jet type recording apparatus is takenas an example of a liquid container and is described below. In general,an ink-jet recording apparatus comprises: a carriage equipped with anink-jet type recording head comprised of a pressure generating meanswhich compresses a pressure generating chamber and a nozzle openingwhich discharges the compressed ink from a nozzle opening in the form ofink droplets; and an ink tank which houses ink supplied to the recordinghead through a passage, and is structured such that the printingoperation can be performed continuously. In general, the ink tank isstructured as a cartridge that can be detached from the recordingapparatus, so that a user can easily replace it at the time when the inkis used up.

Conventionally, as a method of controlling the ink consumption of theink cartridge, a method is known of controlling the ink consumption bymeans of a calculation in which the counted number of ink dropletsdischarged by the recording head and the amount of ink sucked in amaintenance process of the printing head are integrated by software, andanother method of controlling the ink consumption in which the time atwhich the ink is actually consumed is detected by directly mounting tothe ink cartridge two electrodes for use in detecting the liquidsurface, and so forth.

However, in the calculation-based method of controlling the inkconsumption by integrating the discharged number of ink droplets and theamount of ink or the like by the software, the pressure inside the inkcartridge and the viscosity of the ink change depending on usageenvironment such as ambient temperature and humidity, elapsed time afteran ink cartridge has been opened for use, and usage frequency at a userside. Thus, a problem is caused where a considerable error occursbetween the calculated ink consumption and the actual ink consumption.Moreover, another problem is caused in which the actual amount of inkremaining is not known because once the same cartridge is removed andthen mounted again, the integrated counted value is reset.

On the other hand, in the method of controlling by electrodes the timeat which the ink is consumed, the remaining amount of ink can becontrolled with high reliability since the actual ink consumption can bedetected at one point. However, in order that the liquid surface of theink can be detected, the ink need be conductive, so suitable types ofink for use are very limited. Moreover, a problem is caused in that afluid-tight structure between the electrodes and the cartridge might becomplicated. Moreover, since precious metal is usually used as theelectrode material, which is highly conductive and erosive,manufacturing costs of the ink cartridge increases thereby. Moreover,since it is necessary to attach the two electrodes to two separatepositions of the ink cartridge, the manufacturing process increases,thus causing a problem which increases the manufacturing costs.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a liquidconsumption status detecting method and liquid container capable ofaccurately detecting a liquid consumption status and dispensing with acomplicated sealing structure. It is another object of the presentinvention to provide a liquid consumption status detection method, whichis not influenced by the unstable measuring signal generated at theearly stage of the measuring of the liquid consumption status. It is afurther object of the present invention to provide the liquidconsumption status detection method which can reduce the time fordetecting the liquid consumption status. It is still a further object ofthe present invention to provide a control circuit for a measuringapparatus to realize the above mentioned detection method. These objectsare achieved by combinations described in the independent claims. Thedependent claims define further advantageous and exemplary combinationsof the present invention.

According to the first embodiment of the present invention, a method ofdetecting a consumption status of liquid contained in a liquid containeris provided such that the method comprises steps of: preparing adetection device having a piezoelectric element and attaching thedetection device on a desired position of the liquid container so thatat least a part of the detection device contacting the liquid; measuringa residual vibration of the detection device; and detecting theconsumption status of the liquid contained in the liquid container onthe basis of a result of the measurement of the residual vibration.

The detection method may further comprise a step of activating thedetection device to cause a vibration. The detection method can beprovided such that the residual vibration measurement step comprises astep of measuring a frequency of the residual vibration. The detectionmethod can be provided such that the residual vibration measurement stepcomprises a step of measuring a resonance frequency of the liquidsurrounding the detection device.

The detection method can be provided such that the measurement step isoperated after a predetermined time period has elapsed from theactivation step. The detection method can be provided such that themeasurement step is operated after the vibrations of the detectiondevice several times. The detection method can be provided such that themeasurement step comprises a step of measuring a time period in betweena predetermined plurality of peaks of the residual vibration. Thedetection method [according] can be provided such that the measurementstep comprises a step of measuring a number of peaks of the residualvibration within a predetermined time period.

The detection method can be provided such that the measurement stepcomprises a step of measuring a counter electromotive voltage generatedby the detection device in accordance with the residual vibrationthereof. The detection method may further comprise steps of: measuringpreviously a first frequency value of the residual vibration of thedetection device when the liquid container is full of liquid, thefrequency is regarded as a reference frequency value; measuring a secondfrequency value of the residual vibration of the detection device whenliquid in the liquid container is consumed; comparing the referencefrequency with the second frequency; and judging the consumption statusof the liquid contained in the liquid container in accordance with aresult of the comparing step.

The detection method can be provided such that the residual vibrationfrequency measurement step comprises a step of measuring a plurality ofresonance frequency modes of the residual vibration of the detectiondevice. The detection method can be provided such that the measurementstep comprises steps of measuring a first and a second resonancefrequency modes, and recognizing the two resonance frequency modes as asingle pattern.

According to the second aspect of the present invention, a liquidcontainer is provided such that the liquid container comprises: ahousing containing therein liquid; a liquid supply opening formed in thehousing; and a detection device having a piezoelectric element, thedetection device generating a detection signal in accordance with aresidual vibration of the piezoelectric element, the detection signalindicating a consumption status of the liquid contained in the housing.

The liquid container can be provided such that the detection device isactivated to generate a vibration. The liquid container can be providedsuch that the detection signal represents a frequency value of theresidual vibration of the detection device. The liquid container can beprovided such that the detection signal represents a resonance frequencyof the liquid surrounding the detection device. The liquid container canbe provided such that the detection device vibrates at least oneresonance frequency mode.

The liquid container can be provided such that the detection signalrepresents a counter electromotive voltage generated by the detectiondevice in accordance with the residual vibration thereof. The liquidcontainer may further comprise a memory device mounted on the housingfor storing information of the liquid consumption status detected by thedetection device. The liquid container can be provided such that theliquid container is an ink cartridge for an ink jet printer.

According to the third aspect of the present invention, a detectioncontrol circuit for detecting a consumption status of liquid containedin a liquid container by a detection device having a piezoelectricelement can be provided such that the circuit comprises: a measurementcircuit segment for measuring a residual vibration of the detectiondevice; and a detection circuit segment receiving a signal from themeasurement circuit segment and outputting a signal indicative of theconsumption status of the liquid contained in the liquid container onthe basis of the output signal of the measurement circuit segment.

The detection control circuit can be provided such that the measurementcircuit segment measures a frequency of the residual vibration of thedetection device. The detection control circuit can be provided suchthat the measurement circuit segment measures at least one resonancefrequency of the liquid surrounding the detection device. The detectioncontrol circuit can be provided such that the measurement circuitsegment measures a counter electromotive voltage generated by thedetection device in accordance with the residual vibration thereof.

The detection control circuit can be provided such that the measurementcircuit segment comprises an amplifier, the amplifier comprises a PNPtype transistor and a NPN type transistor which complementarilyconnecting with the PNP type transistor, and emitter of the PNP typetransistor and an emitter of the NPN type transistor connect with eachother. A drive voltage generated between a point connecting between theemitter of the NPN type transistor and the PNP type transistor and theground may be applied to the detection device.

The detection control circuit can be provided such that the measurementcircuit segment comprises an amplifier, the amplifier comprises aP-channel field effect transistor and a N-channel field effecttransistor which complementarily connecting with the P-channel fieldeffect transistor, and a source of the P-channel transistor and a sourceof the N-channel transistor connect with each other.

The detection control circuit can be provided such that a drive voltagegenerated between the source of the P-channel FET and the N-channel FETis applied to the detection device. The detection control circuit can beprovided such that the detection circuit segment comprises a counter forcounting the number of the vibrations of the residual vibration within apredetermined time period, and the detection circuit segment judges theliquid consumption status in accordance with the counted value. Thedetection control circuit can be provided such that the detectioncircuit segment comprises a counter for counting a number of clockswithin a time period where the residual vibration vibrates apredetermined number of times, the clock has a cycle shorter than thevibration cycle of the residual vibration.

The detection control circuit can be provided such that the detectioncircuit starts counting the number of vibration of the residualvibration after a predetermined number of vibrations of the residualvibration has occurred. The detection control circuit can be providedsuch that the detection circuit segment outputs a signal representingwhether the liquid container connects with the measurement circuit.

The detection control circuit can be provided such that the measurementcircuit segment further comprises a plurality of amplifiers connectingwith a respective one of a plurality of the detection devices to supplya drive voltage, and the detection circuit segment receives a pluralityof signals from the measurement circuit segment corresponding to therespective detection device and outputting a plurality of signalsindicative of the consumption status of the liquid contained in theliquid container on the basis of each of the output signals of themeasurement circuit segment.

The detection control circuit may further comprise a control circuitsegment for controlling an operation to consume the liquid contained inthe liquid container in accordance with the output signal of thedetection circuit segment. The detection control circuit can be providedsuch that the control circuit segment comprises an information memorycontrol circuit segment for reading out the liquid consumption statusstored in a memory device attached to the liquid container and writingin the memory device information relating to the liquid consumptionstatus detected by the detection circuit segment.

The detection control circuit can be provided such that the liquidcontainer is an ink cartridge for an ink jet printer ejecting inkdroplets from a print head, and the control circuit segment comprising acounter for counting number of ink droplets ejecting from the printhead. The detection control circuit can be provided such that thedetection circuit segment adjust a parameter of an equation forconverting the counted number of the ink droplets into an amount ofliquid consumption in accordance with the consumption status.

According to the fourth aspect of the present invention, acomputer-readable recording medium storing thereon a program for acontrol circuit installed in an ink jet printer to detect a consumptionstatus of ink contained in an ink cartridge by using a detection devicehaving a piezoelectric element attached on a desired position of the inkcartridge can be provided such that the program comprises steps of:measuring a residual vibration of the detection device; and detectingthe consumption status of the ink contained in the ink cartridge on thebasis of a result of the measurement of the residual vibration.

The recording medium may further comprise a step of activating thedetection device to cause a vibration. The recording medium can beprovided such that the residual vibration measurement step comprises astep of measuring a frequency of the residual vibration. The recordingmedium can be provided such that the residual vibration measurement stepcomprises a step of measuring a resonance frequency of ink surroundingthe detection device.

This summary of the invention does not necessarily describe all thenecessary features of the present invention. The present invention mayalso be a sub-combination of the above described features. The above andother features and advantages of the present invention will become moreapparent from the following description of embodiments taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C shows details of the actuator 106.

FIGS. 2A, 2B, 2C, 2D, 2E, and 2F shows periphery and equivalent circuitsof the actuator 106.

FIGS. 3A and 3B show relationship between the ink density and inkresonant frequency detected by the actuator 106.

FIG. 4 shows the relation between a residual quantity of ink inside theink cartridge and combinations of patterns of a primary mode and asecondary mode of the resonant frequency.

FIG. 5 show waveforms of the counter electromotive force of the actuator106.

FIG. 6 shows a configuration of the recording apparatus control unit2000.

FIG. 7 shows a block diagram of the other embodiment of the recordingapparatus control unit 2002.

FIG. 8 shows a further embodiment of the recording apparatus controlunit 2000 shown in FIG. 6.

FIG. 9 shows another embodiment of the recording apparatus control unit2004 shown in FIG. 8.

FIG. 10 shows a flow chart of the operation process of the recordingapparatus control unit 2006.

FIG. 11 shows a circuit configuration of the measuring circuit unit 800.

FIG. 12 shows a circuit configuration of the detecting circuit unit1100.

FIG. 13 shows a detailed circuit configuration of the liquid existencejudging unit 1000 shown in FIG. 12.

FIG. 14 shows another embodiment of the actuator 106.

FIG. 15 shows a cross section of a part of the actuator 106 shown inFIG. 14.

FIG. 16 shows a cross section of the entire actuator 106 shown in FIG.14.

FIG. 17 shows a manufacturing method of the actuator 106 shown in FIG.14.

FIGS. 18A, 18B and 18C show an ink cartridge according to still anotherembodiment of the present invention.

FIGS. 19A, 19B and 19C show another embodiment of the through hole 1 c.

FIG. 20 shows an actuator 660 according to another embodiment.

FIGS. 21A and 21B show an actuator 670 according to still anotherembodiment.

FIG. 22 is a perspective view showing a module 100.

FIG. 23 is an exploded view showing the structure of the module 100shown in FIG. 22.

FIG. 24 shows another embodiment of the module 100.

FIG. 25 is an exploded view showing the structure of the module 400shown in FIG. 24.

FIG. 26 shows still another embodiment of the module 100.

FIG. 27 shows an exemplary cross section of the module 100 shown in FIG.22 where the module 100 is mounted to the ink container.

FIGS. 28A, 28B, and 28C show still another embodiment of the module 100.

FIG. 29 shows an embodiment of an ink cartridge using the actuator 106shown in FIG. 1 and an ink-jet recording apparatus therefor.

FIG. 30 shows a detail of the ink-jet recording apparatus.

FIGS. 31A and 31B show other embodiments of the ink cartridge 180 shownin FIG. 30.

FIGS. 32A, 32B and 32C show still another embodiment of the inkcartridge 180.

FIGS. 33A, 33B and 33C show still another embodiment of the inkcartridge 180.

FIGS. 34A, 34B, 34C and 34D show still another embodiment of the inkcartridge 180.

FIGS. 35A, 35B and 35C show another embodiments of the ink cartridge 180shown in FIG. 34C.

FIGS. 36A and 36B show still another embodiment of the ink cartridgeusing the actuator 106.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described based on the preferred embodiments,which do not intend to limit the scope of the present invention, butexemplify the invention. All of the features and the combinationsthereof described in the embodiment are not necessarily essential to theinvention.

The basic concept of the present invention is to detect a state of theliquid inside a liquid container by utilizing vibration phenomena. Thestate of the liquid includes whether or not the liquid in the liquidcontainer is empty, amount of the liquid, level of the liquid, types ofthe liquid and combination of liquids. Several specific methods fordetection of the state of the liquid inside the liquid containerutilizing vibration phenomena are considered. For example, a method isconsidered in which the medium and the change of its state inside theliquid container are detected in such a manner that an elastic wavegenerating means generates an elastic wave inside the liquid container,and then the reflected wave which is thus reflected by the liquidsurface or a wall disposed counter thereto is captured. There is anothermethod in which a change of acoustic impedance is detected by vibratingcharacteristics of a vibrating object. As a method utilizing the changeof the acoustic impedance, a vibrating portion of a piezoelectric deviceor an actuator having a piezoelectric element therein is vibrated.Thereafter, a resonant frequency or an amplitude of the backelectromotive force waveform is detected by measuring the backelectromotive force which is caused by residual vibration which remainsin the vibrating portion, so as to detect the change of the acousticimpedance. As another method utilizing the change of the acousticimpedance, the impedance characteristic or admittance characteristic ofthe liquid is measured by a measuring apparatus such as an impedanceanalyzer and a transmission circuit, so that the change of a currentvalue or a voltage value, or the change of the current value or voltagevalue due to the frequency caused by the vibration given to the liquidis measured. The operational principles of the elastic wave generatingmeans and the piezoelectric device or actuator will be described at alater stage.

FIG. 1 and FIG. 2 shows a detail and equivalent circuit of an actuator106, which is an embodiment of the piezoelectric device of the presentinvention. The actuator explained herein is used at least for the methodwhich detects the liquid consumption status in the liquid container bydetecting a change in acoustic impedance. Especially, the actuator isused for the method which detects the liquid consumption status in theliquid container by detecting at least the change in acoustic impedanceby detecting the resonant frequency from residual vibration. FIG. 1(A)is an enlarged plan view of the actuator 106. FIG. 1(B) shows a B-Bcross-section of the actuator 106. FIG. 1(C) shows a C-C cross-sectionof the actuator 106. FIG. 2(A) and FIG. 2(B) shows an equivalent circuitof the actuator 106. Each of FIG. 2(C) and FIG. 2(D) shows the actuator106 and around the actuator 106, and the equivalent circuit of theactuator 106 when an ink is filled in the ink cartridge. FIG. 2(E) andFIG. 2(F) shows the actuator 106 and around the actuator 106, and theequivalent circuit of the actuator 106 when there is no ink in the inkcartridge.

The actuator 106 includes abase plate 178, a vibrating plate 176, apiezoelectric layer 160, an upper electrode 164 and a lower electrode166, an upper electrode terminal 168, a lower electrode terminal 170,and a supplementary electrode 172. The base plate 178 has a circularshape opening 161 on approximately its center. The vibrating plate 176is provided on one of the face, which is called as “right side” infollowing, of the base plate 178 such as to cover the opening 161. Thepiezoelectric layer 160 is disposed on right side of the surface of thevibrating plate 176. The upper electrode 164 and the lower electrode 166sandwich the piezoelectric layer 160 from both sides. The upperelectrode terminal 168 connects to the upper electrode 164 electrically.The lower electrode terminal 170 connects to the lower electrode 166electrically. The supplementary electrode 172 is disposed between theupper electrode 164 and the upper electrode terminal 168 and connectsboth of the upper electrode 164 and the upper electrode terminal 168.Each of the piezoelectric layer 160, upper electrode 164, and the lowerelectrode 166 has a circular portion as its main portion. Each of thecircular portion of the piezoelectric layer 160, the upper electrode164, and the lower electrode 166 form a piezoelectric element.

The vibrating plate 176 is formed on the right side of the surface ofthe base plate 178 to cover the opening 161. The cavity 162 is formed bythe portion of the vibrating plate 176, which faces the opening 161, andthe opening 161 of the on the surface of the base plate 178. The face ofthe base plate 178 which is opposite side of the piezoelectric element,called as “back side” in following, is faced with the liquid containerside. The cavity 162 is constructed such that the cavity 162 contactswith liquid. The vibrating plate 176 is mounted on the base plate 178such that the liquid does not leak to the right side of the surface ofthe base plate 178 even if the liquid enters inside the cavity 162.

The lower electrode 166 is located on the right side of the vibratingplate 176, that is, opposite side against the liquid container. Thelower electrode 166 is provided on the vibrating plate 176 such that thecenter of the circular portion of the lower electrode 166, which is amain portion of the lower electrode 166, and the center of the opening161 substantially matches. The area of the circular portion of the lowerelectrode 166 is set to be smaller than the area of the opening 161. Thepiezoelectric layer 160 is formed on the right side of the surface ofthe lower electrode 166 such that the center of the circular portion andthe center of the opening 161 substantially match. The area of thecircular portion of the piezoelectric layer 160 is set to be smallerthan the area of the opening 161 and larger than the area of thecircular portion of the lower electrode 166.

The upper electrode 164 is formed on the right side of the surface ofthe piezoelectric layer 160 such that the center of the circularportion, which is a piezoelectric layer 160, and the center of theopening 161 substantially match. The area of the circular portion of theupper electrode 164 is set to be smaller than the area of the circularportion of the opening 161 and the piezoelectric layer 160 and largerthan the area of the circular portion of the lower electrode 166.

Therefore, the main portion of the piezoelectric layer 160 has astructure to be sandwiched by the main portion of the upper electrode164 and the main portion of the lower electrode each from right sideface and back side face, and thus the main portion of the piezoelectriclayer 160 can effectively drive and deform the piezoelectric layer 160.The circular portion, which is a main portion of each of thepiezoelectric layer 160, the upper electrode 164, and the lowerelectrode 166, forms the piezoelectric element in the actuator 106. Asexplained above, the electric element contacts with the vibrating plate.Within the circular portion of the upper electrode 164, circular portionof the piezoelectric layer 160, the circular portion of the lowerelectrode, and the opening 161, the opening 161 has the largest area. Bythis structure, the vibrating region which actually vibrates within thevibrating plate is determined by the opening 161. Furthermore, each ofthe circular portion of the upper electrode 164 and the circular portionof the piezoelectric layer 160 and the circular portion of the lowerelectrode has smaller area than the area of the opening 161. Thevibrating plate becomes easily vibrateable. Within the circular portionof the lower electrode 166 and the circular portion of the upperelectrode 164 which connects to the piezoelectric layer 160electrically, the circular portion of the lower electrode 166 is smallerthan the circular portion of the upper electrode 164. Therefore, thecircular portion of the lower electrode 166 determines the portion whichgenerates the piezoelectric effect within the piezoelectric layer 160.

The center of the circular portion of the piezoelectric layer 160, theupper electrode 164, and the lower electrode 166, which form thepiezoelectric element, substantially match to the center of the opening161. Moreover, the center of the circular shape opening 161, whichdetermines the vibrating section of the vibrating plate 176, is providedon the approximately center of the actuator 106. Therefore, the centerof the vibrating section of the actuator 106 matches to the center ofthe actuator 106. Because the main portion of the piezoelectric elementand the vibrating section of the vibrating plate 176 have a circularshape, the vibrating section of the actuator 106 is symmetrical about acenter of the actuator 106.

Because the vibrating section is symmetrical about a center of theactuator 106, the excitation of the unnecessary vibration occurred owingto the asymmetric structure can be prevented. Therefore, the accuracy ofdetecting the resonant frequency increases. Furthermore, because thevibrating section is symmetric about the center of the actuator 106, theactuator 106 is easy to manufacture, and thus the unevenness of theshape for each of the piezoelectric element can be decreased. Therefore,the unevenness of the resonant frequency for each of the piezoelectricelement 174 decreases. Furthermore, because the vibrating section has anisotropic shape, the vibrating section is difficult to be influenced bythe unevenness of the fixing during the bonding process. That is, thevibrating section is bonded to the liquid container uniformly.Therefore, the actuator 106 is easy to assemble to the liquid container.

Furthermore, because the vibrating section of the vibrating plate 176has a circular shape, the lower resonant mode, for example, the primaryresonant mode dominates on the resonant mode of the residual vibrationof the piezoelectric layer 160, and thus the single peak appears on theresonant mode. Therefore, the peak and the noise can be distinguishedclearly so that the resonant frequency can be clearly detected.Furthermore, the accuracy of the detection of the resonant frequency canbe further increased by enlarging the area of the vibrating section ofthe circular shaped vibrating plate 176, because the difference of theamplitude of the counter electromotive force, and the difference of theamplitude of the resonant frequency that occurs depending on whether theliquid exists inside the liquid container, increase.

The displacement generated by the vibration of the vibrating plate 176is larger than the displacement generated by the vibration of the baseplate 178. The actuator 106 has a two layer structure that isconstituted by the base plate 178 having a small compliance which meansit is difficult to be displaced by the vibration, and the vibratingplate 176 having a large compliance which means it is easy to bedisplaced by the vibration. By this two layer structure, the actuator106 can be reliably fixed to the liquid container by the base plate 178and at the same time the displacement of the vibrating plate 176 by thevibration can be increased. Therefore, the difference of the amplitudeof the counter electromotive force and the difference of the amplitudeof the resonant frequency depends on whether the liquid exists insidethe liquid container increases, and thus the accuracy of the detectionof the resonant frequency increases. Furthermore, because the complianceof the vibrating plate 176 is large, the attenuation of the vibrationdecreases so that the accuracy of the detection of the resonantfrequency increases. The node of the vibration of the actuator 106locates on the periphery of the cavity 162, that is, around the marginof the opening 161.

The upper electrode terminal 168 is formed on the right side of thesurface of the vibrating plate 176 to be electrically connected to theupper electrode 164 through the supplementary electrode 172. The lowerelectrode terminal 170 is formed on the right side of the surface of thevibrating plate 176 to be electrically connected to the lower electrode166. Because the upper electrode 164 is formed on the right side of thepiezoelectric layer 160, there is a difference in depth that is equal tothe sum of the thickness of the piezoelectric layer 160 and thethickness of the lower electrode 166 between the upper electrode 164 andthe upper electrode terminal 168. It is difficult to fill thisdifference in depth only by the upper electrode 164, and even it ispossible to fill the difference in depth by the upper electrode 164, theconnection between the upper electrode 164 and the upper electrodeterminal 168 becomes weak so that the upper electrode 164 will be cutoff. Therefore, this embodiment uses the supplementary electrode 172 asa supporting member to connects the upper electrode 164 and the upperelectrode terminal 168. By this supplementary electrode 172, both of thepiezoelectric layer 160 and the upper electrode 164 are supported by thesupplementary electrode 172, and thus the upper electrode 164 can havedesired mechanical strength, and also the upper electrode 164 and theupper electrode terminal 168 can be firmly connected.

The piezoelectric element and the vibrating section which faces to thepiezoelectric element within the vibrating plate 176 constitute thevibrating section which actually vibrates in the actuator 106. Moreover,it is preferable to form the actuator 106 in one body by firing togetherthe member included in the actuator 106. By forming the actuator 106 asone body, the actuator 106 becomes easy to be handled. Further, thevibration characteristic increases by increasing the strength of thebase plate 178. That is, by increasing the strength of the base plate178, only the vibrating section of the actuator 106 vibrates, and theportion other than the vibrating section of the actuator 106 does notvibrates. Furthermore, the prevention of the vibration of the portionother than the vibrating section of the actuator 106 can be achieved byincreasing the strength of the base plate 178 and at the same timeforming the actuator 106 as thinner and smaller as possible and formingthe vibrating plate 176 as thinner as possible.

It is preferable to use lead zirconate titanate (PZT), lead lanthanumzirconate titanate (PLZT), or piezoelectric membrane without using leadas a material for the piezoelectric layer 160. It is preferable to usezirconia or alumina as a material of the base plate 178. Furthermore, itis preferable to use the same material as base plate 178 for a materialof vibrating plate 176. The metal such as gold, silver, copper, platina,aluminum, and nickel having an electrical conductivity can be used forthe material of the upper electrode 164, the lower electrode 166, theupper electrode terminal 168, and the lower electrode terminal 170.

The actuator 106 constructed as explained above can be applied to thecontainer which contains liquid. For example, the actuator 106 can bemounted on an ink cartridge used for the ink jet recording apparatus, anink tank, or a container which contains washing liquid to wash therecording head.

The actuator 106 shown in the FIG. 1 and FIG. 2 is mounted on thepredetermined position on the liquid container so that the cavity 162can contact with the liquid contained inside the liquid container. Whenthe liquid container is filled with liquid sufficiently, the inside andoutside of the cavity 162 is filled with liquid. On the other hand, ifthe liquid inside the liquid container is consumed and the liquid levelis decreased under the mounting position of the actuator, there areconditions that liquid does not exist inside the cavity 162 or thatliquid is remained only in the cavity 162 and air exists outside thecavity 162. The actuator 106 detects at least the difference in theacoustic impedance occurred by this change in condition. By thisdetection of the difference in acoustic impedance, the actuator 106 candetect whether the liquid is sufficiently filled in the liquid containeror liquid is consumed more than the predetermined level. Furthermore,the actuator 106 can detect the type of the liquid inside the liquidcontainer.

The principle of the detection of the liquid level by the actuator willbe explained.

To detect the acoustic impedance of a medium, an impedancecharacteristic or an admittance characteristic is measured. To measurethe impedance characteristic or the admittance characteristic, forexample, a transmission circuit can be used. The transmission circuitapplies a constant voltage on the medium and [measure] measures acurrent flow through the medium with changing a frequency. Thetransmission circuit provides a constant current to the medium andmeasures a voltage applied on the medium with changing a frequency. Thechange in current value and the voltage value measured at thetransmission circuit shows the change in acoustic impedance.Furthermore, the change in a frequency fm, which is a frequency when thecurrent value or the voltage value becomes maximum or minimum, alsoshows the change in acoustic impedance.

Other than method shown above, the actuator can detects the change inthe acoustic impedance of the liquid using the change only in theresonant frequency. The piezoelectric element, for example, can be usedin a case of using the method of detecting the resonant frequency bymeasuring the counter electromotive force generated by the residualvibration, which is remained in the vibrating section after thevibration of the vibrating section of the actuator, as a method of usingthe change in the acoustic impedance of the liquid. The piezoelectricelement is element which generates the counter electromotive force byresidual vibration remained in the vibrating section of the actuator.The magnitude of the counter electromotive force changes with theamplitude of the vibrating section of the actuator. Therefore, thelarger the amplitude of the vibrating section of the actuator, theeasier to detect the resonant frequency. Moreover, depends on thefrequency of the residual vibration at the vibrating section of theactuator, the period, on which the magnitude of the counterelectromotive force changes, changes. Therefore, the frequency of thevibrating section of the actuator corresponds to the frequency of thecounter electromotive force. Here, the resonant frequency means thefrequency when the vibrating section of the actuator and the medium,which contacts to the vibrating section, are in a resonant condition.

To obtain the resonant frequency fs, the waveform obtained by measuringthe counter electromotive force when the vibrating section and themedium are in resonant condition is Fourier transformed. Because thevibration of the actuator is not a displacement for only one direction,but the vibration involves the deformation such as deflection andextension, the vibration has various kinds of frequency including theresonant frequency fs. Therefore, the resonant frequency fs is judged byFourier transforming the waveform of the counter electromotive forcewhen the piezoelectric element and the medium are in the resonantcondition and then specifying the most dominating frequency components.

The frequency fm is a frequency when the admittance of the medium ismaximum or the impedance is minimum. The frequency fm is different fromthe resonant frequency fs with little value because of the dielectricloss and the mechanical loss. However, the frequency fm is generallyused as substitution for resonant frequency because it needs time forderiving the resonant frequency fs from the frequency fm which isactually measured. By inputting output of the actuator 106 to thetransmission circuit, the actuator 106 can at least detect the acousticimpedance.

It is proved by the experiment that there is almost no differences withthe resonant frequency obtained by the method, which measures thefrequency fm by measuring the impedance characteristic and admittancecharacteristic of the medium, and the method, which measures theresonant frequency fs by measuring the counter electromotive forcegenerated by the residual vibration at the vibrating section of theactuator.

The vibrating region of the actuator 106 is a portion which constitutesthe cavity 162 that is determined by the opening 161 within thevibrating plate 176. When liquid is sufficiently filled in the liquidcontainer, liquid is filled in the cavity 162, and the vibrating regioncontacts with liquid inside the liquid container. When liquid does notexists in the liquid container sufficiently, the vibrating regioncontacts with the liquid which is remained in the cavity inside theliquid container, or the vibrating region does not contacts with theliquid but contacts with the gas or vacuum.

The cavity 162 is provided on the actuator 106 of the present invention,and it can be designed that the liquid inside the liquid containerremains in the vibrating region of the actuator 106 by the cavity 162.The reason will be explained as follows.

Depending on the mounting position and mounting angle of the actuator106 on the liquid container, there is a case in which the liquidattaches to the vibrating region of the actuator even if the liquidlevel in the liquid container is lower than the mounting position of theactuator. When the actuator detects the existence of the liquid onlyfrom the existence of the liquid on the vibrating region, the liquidattached to the vibrating region of the actuator prevents the accuratedetection of the existence of the liquid. For example, if the liquidlevel is lower than the mounting position of the actuator, and the dropof the liquid attaches to the vibrating region by the waving of theliquid caused by the shaking of the liquid container caused by themovement of the carriage, the actuator 106 will misjudge that there isenough liquid in the liquid container. In this way, the malfunction canbe prevented by using the actuator having a cavity.

Furthermore, as shown in FIG. 2(E), the case when the liquid does notexit in the liquid container and the liquid of the liquid containerremains in the cavity 162 of the actuator 106 is set as the thresholdvalue of the existence of the liquid. That is, if the liquid does notexist around the cavity 162, and the amount of the liquid in the cavityis smaller than this threshold value, it is judged that there is no inkin the liquid container. If the liquid exist around the cavity 162, andthe amount of the liquid is larger than this threshold value, it isjudged that there is ink in the liquid container. For example, when theactuator 106 is mounted on the side wall of the liquid container, it isjudged that there is no ink in the liquid container when the liquidlevel inside the liquid container is lower than the mounting position ofthe actuator 106, and it is judged that there is ink inside the liquidcontainer when the liquid level inside the liquid container is higherthan the mounting position of the actuator 106. By setting the thresholdvalue in this way, the actuator 106 can judge that there is no ink inthe liquid container even if the ink in the cavity is dried anddisappeared. Furthermore, the actuator 106 can judge that there is noink in the liquid container even if the ink attaches to the cavity againby shaking of the carriage after the ink in the cavity disappearsbecause the amount of the ink attaches to the cavity again does notexceed the threshold value.

The operation and the principle of detecting the liquid condition of theliquid container from the resonant frequency of the medium and thevibrating section of the actuator 106 obtained by measuring the counterelectromotive force will be explained reference to FIG. 1 and FIG. 2. Avoltage is applied on each of the upper electrode 164 and the lowerelectrode 166 through the upper electrode terminal 168 and the lowerelectrode terminal 170. The electric field is generated on the portionof the piezoelectric layer 160 where the piezoelectric layer 160 issandwiched by the upper electrode 164 and the lower electrode 166. Bythis electric field, the piezoelectric layer 160 deforms. By thedeformation of the piezoelectric layer 160, the vibrating region withinthe vibrating plate 176 deflects and vibrates. For some period after thedeformation of the piezoelectric layer 160, the vibration withdeflection remains in the vibrating section of the actuator 106.

The residual vibration is a free oscillation of the vibrating section ofthe actuator 106 and the medium. Therefore, the resonant conditionbetween the vibrating section and the medium can be easily obtained byapplying the voltage of a pulse wave or a rectangular wave on thepiezoelectric layer 160. Because the residual vibration vibrates thevibrating section of the actuator 106, the residual vibration alsodeforms the piezoelectric layer 160. Therefore, the piezoelectric layer160 generates the counter electromotive force. This counterelectromotive force is detected through the upper electrode 164, thelower electrode 166, the upper electrode terminal 168, and the lowerelectrode terminal 170. Because the resonant frequency can be specifiedby this detected counter electromotive force, the liquid consumptionstatus in the liquid container can be detected.

Generally, the resonant frequency fs can be expressed as the following:fs=1/(2*π*(M*Cact)^(1/2)   (1)where M denotes the sum of an inertance of the vibrating section Mactand an additional inertance M′; Cact denotes a compliance of thevibrating section.

FIG. 1(C) shows a cross section of the actuator 106 when the ink doesnot exist in the cavity in the present embodiment. FIG. 2(A) and FIG.2(B) shows the equivalent circuit of the vibrating section of theactuator 106 and the cavity 162 when the ink does not exist in thecavity.

The Mact is obtained by dividing the product of the thickness of thevibrating section and the density of the vibrating section by the areaof the vibrating section. Furthermore, as shown in the FIG. 2(A), theMact can be expressed as following in detail.Mact=Mpzt+Melectrode1+Melectrode2+Mvib   (2)Here, Mpzt is obtained by dividing the product of the thickness of thepiezoelectric layer 160 in the vibrating section and the density of thepiezoelectric layer 160 by the area of the piezoelectric layer 160.Melectrode1 is obtained by dividing the product of the thickness of theupper electrode 164 in the vibrating section and the density of theupper electrode 164 by the area of the upper electrode 164. Melectrode2is obtained by dividing the product of the thickness of the lowerelectrode 166 in the vibrating section and the density of the lowerelectrode 166 by the area of the lower electrode 166. Mvib is obtainedby dividing the product of the thickness of the vibrating plate 176 inthe vibrating section and the density of the vibrating plate 176 by thearea of the vibrating region of the vibrating plate 176. However each ofthe size of the area of the vibrating region of the piezoelectric layer160, the upper electrode 164, the lower electrode 166, and vibratingplate 176 have a relationship as shown above, the difference among eachof the area of the vibrating region is prefer to be microscopic toenable the calculation of the Mact from the thickness, density, and areaas whole of the vibrating section. Moreover, it is preferable that theportion other than the circular portion which is a main portion of eachof the piezoelectric layer 160, the upper electrode 164, and the lowerelectrode 166 is microscopic so that it can be ignored compared to themain portion. Therefore, Mact is sum of the inertance of the each of thevibrating region of the upper electrode 164, the lower electrode 166,the piezoelectric layer 160, and the vibrating plate 176 in the actuator106. Moreover, the compliance Cact is a compliance of the portion formedby the each of the vibrating region of the upper electrode 164, thelower electrode 166, the piezoelectric layer 160, and the vibratingplate 176.

FIG. 2(A), FIG. 2(B), FIG. 2(D), and FIG. 2(F) show the equivalentcircuit of the vibrating section of the actuator 106 and the cavity 162.In these equivalent circuits, Cact shows a compliance of the vibratingsection of the actuator 106. Each of the Cpzt, Celectrode1, Celectrode2,and Cvib shows the compliance of the vibrating section of thepiezoelectric layer 160, the upper electrode 164, the lower electrode166, and the vibrating plate 176. Cact can be shown as followingequation.1/Cact=(1/Cpzt)+(1/Celectrode1)+(1/Celectrode2)+(1/Cvib)   (3)

From the equation (2) and (3), FIG. 2(A) can be expressed as FIG. 2(B).

The compliance Cact shows the volume which can accept the medium by thedeformation generated by the application of the pressure on the unitarea of the vibrating section. In other words, the compliance Cact showsthe easiness to be deformed.

FIG. 2(C) shows the cross section of the actuator 106 when the liquid issufficiently filled in the liquid container, and the periphery of thevibrating region of the actuator 106 is filled with the liquid. TheM′max shown in FIG. 2(C) shows the maximum value of the additionalinertance when the liquid is sufficiently filled in the liquidcontainer, and the periphery of the vibrating region of the actuator 106is filled with the liquid. The M′max can be expressed asM′max=(π*ρ/(2*k ³))*(2*(2*k*a)³/(3*π))/(λ*a ²)²   (4)where “a” denotes the radius of the vibrating section; ρ denotes thedensity of the medium; and k denotes the wave number. The equation (4)applies when the vibrating region of the actuator 106 is a circularshape having the radius of “a”. The additional inertance M′ shows thequantity that the mass of the vibrating section is increased virtuallyby the effect of the medium which exists around the vibrating section.

As shown in equation (4), the M′max can changes significantly by theradius of the vibrating section “a” and the density of the medium ρ.

The wave number k can be expressed by following equation.k=2*π*fact/c   (5)where fact denotes the resonant frequency of the vibrating section whenthe liquid does not contact with the vibrating section; and “c” denotesthe speed of the sound propagate through the medium.

FIG. 2(D) shows an equivalent circuit of the vibrating section of theactuator 106 and the cavity 162 as in the case of FIG. 2(C) when theliquid is sufficiently filled in the liquid container, and the peripheryof the vibrating region of the actuator 106 is filled with the liquid.

FIG. 2(E) shows the cross section of the actuator 106 when the liquid inthe liquid container is consumed, and there is no liquid around thevibrating region of the actuator 106, and the liquid remains in thecavity 162 of the actuator 106. The equation (4) shows the maximuminertance M′max determined by such as the ink density ρ when the liquidcontainer is filled with the liquid. On the other hand, if the liquid inthe liquid container is consumed and liquid existed around the vibratingsection of the actuator 106 becomes gas or vacuum with the liquidremaining in the cavity 162, the M′ can be expressed as followingequation.M′=ρ*t/S   (6)where t denotes the thickness of the medium related to the vibration;“S” denotes the area of the vibrating region of the actuator 106. Ifthis vibrating region is a circular shape having a radius of “a”, the“S” can be shown as S=π*a². Therefore, the additional inertance M′follows the equation (4) when the liquid is sufficiently filled in theliquid container, and the periphery of the vibrating region of theactuator 106 is filled with the liquid. The additional inertance M′follows the equation (6) when the liquid in the liquid container isconsumed, there is no liquid around the vibrating region of the actuator106, and the liquid remains in the cavity 162.

Here, as shown in FIG. 2(E), let the additional inertance M′, when theliquid in the liquid container is consumed, there is no liquid aroundthe vibrating region of the actuator 106, and the liquid remains in thecavity 162, be M′ cav to distinguish with the additional inertance M′max, which is the additional inertance when the periphery of thevibrating region of the actuator 106 is filled with the liquid.

FIG. 2(F) shows an equivalent circuit of the vibrating section of theactuator 106 and the cavity 162 in the case of FIG. 2(E) when the liquidin the liquid container is consumed, and there is no liquid around thevibrating region of the actuator 106, and the liquid remains in thecavity 162 of the actuator 106.

Here, the parameters related to the status of the medium are density ofthe medium p and the thickness of the medium t in equation (6). When theliquid is sufficiently filled in the liquid container, the liquidcontacts with the vibrating section of the actuator 106. When the liquidis insufficiently filled in the liquid container, the liquid is remainedin the cavity, or the gas or vacuum contacts with the vibrating sectionof the actuator 106. If the additional inertance-during the process ofthe shifting from the M′max of FIG. 2(C) to the M′var of FIG. 2(E) whenthe liquid around the actuator 106—is consumed, because the thickness ofthe medium “t” changes according to the containing status of the liquidin the liquid container, the additional inertance M′var changes, andresonant frequency also changes. Therefore, the existence of the liquidin the liquid container can be detected by specifying the resonantfrequency. Here, if t=d, as shown in FIG. 2(E) and using the equation(6) to express the M′cav, the equation (7) can be obtained bysubstituting the thickness of the cavity “d” into the “t” in theequation (6).M′cav=ρ*d/S   (7)

Moreover, if the medium are different types of liquid with each other,the additional inertance M′ changes and resonant frequency fs alsochanges because the density ρ is different according to the differenceof the composition. Therefore, the types of the liquid can be detectedby specifying the resonant frequency fs. Moreover, when only one of theink or air contacts with the vibrating section of the actuator 106, andthe ink and air is not existing together, the difference in M′ can bedetected by calculating the equation (4).

FIG. 3(A) is a graph which shows the relationship between the inkquantity inside the ink tank and the resonant frequency fs of the inkand the vibrating section. Here, the case for the ink will be explainedas an example of the liquid. The vertical axis shows the resonantfrequency fs, and the horizontal axis shows the ink quantity. When theink composition is constant, the resonant frequency increases accordingto the decreasing of the ink quantity.

When ink is sufficiently filled in the ink container, and ink is filledaround the vibrating region of the actuator 106, the maximum additionalinertance M′max becomes the value shown in the equation (4). When theink is consumed, and there is no ink around the vibrating region of theactuator 106, and the ink remains in the cavity 162, the additionalinertance M′var is calculated by the equation (6) based on the thicknessof the medium “t”. Because the “t” used in the equation (6) is thethickness of the medium related to the vibration, the process duringwhich the ink is consumed gradually can be detected by forming the “d”(refer to FIG. 1(B)) of the cavity 162 of the actuator 106 as small aspossible, that is, forming the thickness of the base plate 178 assufficiently thinner as possible (refer to FIG. 2(C)). Here, let t-inkbe the thickness of the ink involved with the vibration and t-ink-max bethe value of t-ink when the additional inertance is M′max. For example,the actuator 106 is mounted on the bottom of the ink cartridgehorizontally to the surface of the ink. If ink is consumed, and the inklevel becomes lower than the height t-ink-max from the actuator 106, theM′var gradually changes according to the equation (6), and the resonantfrequency fs gradually changes according to the equation (1). Therefore,until the ink level is within the range of “t”, the actuator 106 cangradually detect the ink consumption status.

Furthermore, by enlarge or lengthen the vibrating section of theactuator 106 and arrange the actuator 106 along a lengthwise direction,the “S” in the equation (6) changes according to the change of ink levelwith ink consumption. Therefore, the actuator 106 can detect the processwhile the ink is gradually consumed. For example, the actuator 106 ismounted on the side wall of the ink cartridge perpendicularly to the inksurface. When the ink is consumed and the ink level reaches to thevibrating region of the actuator 106, because the additional inertanceM′ decreases with the decreasing of the ink level, the resonantfrequency fs gradually increases according to the equation (1).Therefore, unless the ink level is within the range of the radius 2 a ofthe cavity 162 (refer to FIG. 2(C)), the actuator 106 can graduallydetect the ink consumption status.

The curve X in FIG. 3(A) shows the relationship between the ink quantitycontained inside of the ink tank and the resonant frequency fs of theink and the vibrating section when the vibrating region of the actuator106 is formed sufficiently large or long. It can be understand that theresonant frequency fs of the ink and vibrating section gradually changeswith the decrease of the ink quantity inside the ink tank.

In detail, the case when the actuator 106 can detect the process of thegradual consumption of the ink is the case when the liquid and gashaving different density with each other are existed together and alsoinvolved with vibration. According to the gradual consumption of theink, the liquid decreases with increasing of the gas in the mediuminvolved with the vibration around the vibrating region of the actuator106. For example, the case when the actuator 106 is mounted on the inkcartridge horizontally to the ink surface, and t-ink is smaller than thet-ink-max, the medium involved with the vibration of the actuator 106includes both of the ink and the gas. Therefore, the following equation(8) can be obtained if the area of the vibrating region of the actuator106 is “S” and the status when the additional inertance is below M′maxin the equation (4) is expressed by additional mass of the ink and thegas.M′=M′air+M′ink=ρair*t−air/S+ρink*t−ink/S   (8)where M′max is an inertance of an air; M′ink is an inertance of an ink;ρair is a density of an air; ρink is a density of an ink; t-air is thethickness of the air involved with the vibration; and t-ink is thethickness of the ink involved with the vibration. In case when theactuator 106 is mounted on the ink cartridge approximately horizontallyto the ink surface, the t-air increases and the t-ink decreases with theincrease of the gas and the decrease of the ink within the mediuminvolved with the vibration around the vibrating region of the actuator106. The additional inertance M′ gradually decreases, and the resonantfrequency gradually increases by above changes of the t-air and thet-ink. Therefore, the ink quantity remained inside the ink tank or theink consumption quantity can be detected. The equation (7) depends onlyon the density of the liquid because of the assumption that the densityof the air is small compare to the density of the liquid so that thedensity of the air can be ignored.

When the actuator 106 is provided on the ink cartridge substantiallyperpendicular to the ink surface, the status can be expressed as theequivalent circuit, not shown in the figure, on which the region, wherethe medium involved with the vibration of the actuator 106 is ink only,and the region, where the medium involved with the vibration of theactuator 106 is gas, can be expressed as parallel circuit. If the areaof the region where the medium involved with the vibration of theactuator 106 is ink only, expressed as Sink, and if the area of theregion where the medium involved with the vibration of the actuator 106is gas only, expressed as Sair, the following equation (9) can beobtained.1/M′=1/M′air+1/M′ink=Sair/(ρair*t−air)+Sink/(ρink*t−ink)   (9)

The equation (9) can be applied when the ink is not held in the cavityof the actuator 106. The case when the ink is held in the cavity can becalculated using the equation (7), (8), and (9).

In the case when the thickness of the base plate 178 is thick, that is,the depth of the cavity 162 is deep and “d” is comparatively close tothe thickness of the medium t-ink-max, or in the case when using anactuator having a very small vibrating region compared to height of theliquid container, the actuator does not detect the process of thegradual decrease of the ink but actually detects whether the ink levelis higher or lower than the mounting position of the actuator. In otherwords, the actuator detects the existence of the ink at the vibratingregion of the actuator. For example, the curve Y in FIG. 3(A) shows therelationship between the ink quantity in the ink tank and the resonantfrequency fs of the vibrating section when the vibrating section issmall circular shape. The curve Y shows that the resonant frequency fsof the ink and the vibrating section changes extremely during the rangeof change of ink quantity Q, which corresponds to the status before andafter the ink level in the ink tank passes the mounting position of theactuator. By this change of the resonant frequency fs, it can bedetected whether the ink quantity remained in the ink tank is more thanthe predetermined quantity.

The method of using the actuator 106 for detecting the existence of theliquid is more accurate than the method which calculates the quantity ofink consumption by the software because the actuator 106 detects theexistence of the ink by directly contacting with the liquid.Furthermore, the method using an electrode to detect the existence ofthe ink by conductivity is influenced by the mounting position to theliquid container and the ink type, but the method using the actuator 106to detect the existence of the liquid is not influenced by the mountingposition to the liquid container, or by the ink type. Moreover, becauseboth of the oscillation and detection of the existence of the liquid canbe done by the single actuator 106, the number of the sensor mounted onthe liquid container can be reduced compared to the method usingseparate sensor for oscillation and the detection of the existence ofthe liquid. Therefore, the liquid container can be manufactured at a lowprice. Furthermore, the sound generated by the actuator 106 during theoperation of the actuator 106 can be reduced by setting the vibratingfrequency of the piezoelectric layer 160 out of the audio frequency.

FIG. 3(B) shows the relationship between the density of the ink and theresonant frequency fs of the ink and the vibrating section of the curveY shown in FIG. 3(A). Ink is used as an example of liquid. As shown inFIG. 3(B), when ink density increases, the resonant frequency fsdecreases because the additional inertance increases. In other words,the resonant frequency fs is different depending on the type of the ink.Therefore, by measuring the resonant frequency fs, it can be confirmedwhether the ink of a different density has been mixed together duringthe re-filling of the ink to the ink tank.

Therefore, the actuator 106 can distinguish the ink tank which containsthe different type of the ink.

The condition when the actuator 106 can accurately detect the status ofthe liquid will be explained in detail in following. The case is assumedthat the size and the shape of the cavity is designed so that the liquidcan be remained in the cavity 162 of the actuator 106 even when theliquid inside the liquid container is empty. The actuator 106 can detectthe status of the liquid even when the liquid is not filled in thecavity 162 if the actuator 106 can detect the status of the liquid whenthe liquid is filled in the cavity 162.

The resonant frequency fs is a function of the inertance M. Theinertance M is a sum of the inertance of the vibrating section Mact andthe additional inertance M′. Here, the additional inertance M′ has therelationship with the status of the liquid. The additional inertance M′is a quantity of a virtual increase of a mass of the vibrating sectionby the effect of the medium existed around the vibrating section. Inother words, the additional inertance M′ is the amount of increase ofthe mass of the vibrating section which is increased by the vibration ofthe vibrating section that virtually absorbs the medium.

Therefore, when the M′cav is larger than the M′max in the equation (4),all the medium which is virtually absorbed is the liquid remained in thecavity 162. Therefore, the status when the M′cav is larger than theM′max is same with the status that the liquid container is fill withliquid. The resonant frequency fs does not change because the M′ doesnot change in this case. Therefore, the actuator 106 cannot detect thestatus of the liquid in the liquid container.

On the other hand, if the M′cav is smaller than the M′max in theequation (4), the medium which is virtually absorbed is the liquidremained in the cavity 162 and the gas or vacuum in the liquidcontainer. In this case, because the M′ changes, which is different withthe case when the liquid is filled in the liquid container, the resonantfrequency fs changes. Therefore, the actuator 106 can detect the statusof the liquid in the liquid container.

The condition whether the actuator 106 can accurately detect the statusof the liquid is that the M′cav is smaller than the M′max when theliquid is remained in the cavity 162 of the actuator 106, and the liquidcontainer is empty. The condition M′max>M′cav, on which the actuator 106can accurately detect the status of the liquid, does not depend on theshape of the cavity 162.

Here, the M′cav is the mass of the liquid of the volume which issubstantially equal to the volume of the cavity 162. Therefore, thecondition, which can detect the status of the liquid accurately, can beexpressed as the condition of the volume of the cavity 162 from theinequality M′max>M′cav. For example, if the radius of the opening 161 ofthe circular shaped cavity 162 is “a” and the thickness of the cavity162 is “d”, then the following inequality can be obtained:M′max>ρ*d/πa ²   (10)By expanding the inequality (10), the following condition can beobtained.a/d>3*π/8   (11)The inequalities (10) and (11) are valid only when the shape of thecavity 162 is circular. By using the equation when the M′max is notcircular and substituting the area πa² with its area, the relationshipbetween the dimension of the cavity such as a width and a length of thecavity and the depth can be derived.

Therefore, if the actuator 106 has the cavity 162 which has the radiusof the opening 161 “a” and the depth of the cavity “d” that satisfy thecondition shown in inequality (11), the actuator 106 can detect theliquid status without malfunction even when the liquid container isempty and the liquid is remained in the cavity 162.

Because the additional inertance influences the acoustic impedancecharacteristic, it can be said that the method of measuring the counterelectromotive force generated in actuator 106 by residual vibrationmeasures at least the change of the acoustic impedance.

Furthermore, according to the present embodiment, the actuator 106generates the vibration, and the actuator 106 itself measures thecounter electromotive force in actuator 106 which is generated by theresidual vibration remained after the vibration of the actuator 106.However, it is not necessary for the vibrating section of the actuator106 to provide the vibration to the liquid by the vibration of theactuator 106 itself which is generated by the driving voltage. Even thevibrating section itself does not oscillates, the piezoelectric layer160 deflects and deforms by vibrates together with the liquid, whichcontacts with the vibrating section with some range. This residualvibration generates the counter electromotive force voltage in thepiezoelectric layer 160 and transfer this counter electromotive forcevoltage to the upper electrode 164 and the lower electrode 166. Thestatus of the liquid can be detected using this phenomenon. For example,in case of the ink jet recording apparatus, the status of the ink tankor the ink contained inside the ink tank can be detected using thevibration around the vibrating section of the actuator which isgenerated by the vibration generated by the reciprocating motion of thecarriage to scanning the print head during the printing operation.

Preferably, the actuator 106 oscillates the frequency in inaudibleregion. For example, the frequency is preferably from 100 kHz to 500kHz. Recently, because the noise generated by the ink jet recordingapparatus during the operation becomes extremely small, the noisegenerated by the actuator 106 will become conspicuous relative to thenoise generated by the ink jet recording apparatus if the frequencygenerated by the actuator 106 during the driving of the actuator 106 isin audible frequency. Then, the user of the ink jet recording apparatusmay feel uncomfortable. Therefore, it is desirable to set the frequencygenerated by the actuator 106 to be a frequency in inaudible region sothat the user of the ink jet recording apparatus does not feel thevibration generated by the actuator 106 as uncomfortable.

Even if each of the ink cartridges of the same type contain the samekinds of, for example, same color of ink with same quantity, the valueof the generated resonant frequency are subtly different for each inkcartridges owing to a difference in each individual actuators 106.Therefore, the frequency is measured when an ink cartridge is inink-full status, and the data of the frequency is previously stored inthe semiconductor memory device 7 or the memory inside the recordingapparatus. Then, by comparing the frequency measured during theconsumption of the ink in each ink cartridge with the frequency storedin the memory as a reference value, the ink consumption status can bedetected for each ink cartridge. For example, the frequency when the inkcartridge is in ink-full status is measured when the new ink cartridgeis mounted on the recording apparatus, and the value of the frequency isstored in the memory as a reference value. Then, the ink consumptionstatus can be detected by comparing the frequency measured when the inkin the ink cartridge is consumed with the frequency when the inkcartridge is in ink-full status as a reference value. Moreover, thefrequency when the ink cartridge is in ink-full status is previouslymeasured during the manufacturing process of the ink cartridge, and thevalue of the measured frequency is stored in the semiconductor memorydevice 7 as a reference value. Then, the ink consumption status can bedetected by comparing the frequency measured when the ink in the inkcartridge is consumed with the frequency when the ink cartridge is inink-full status as a reference value.

FIG. 4 shows the relation between a residual quantity of ink inside theink cartridge and combinations of patterns of a primary mode and asecondary mode of the resonant frequency. The value of the combinationof the patterns among a primary mode resonant frequency, secondary moderesonant frequency, and a combination of the primary mode and asecondary mode of a resonant frequency are shown for each of the inkcartridge having different residual quantity of ink.

A primary mode is a primary frequency of a waveform of a counterelectromotive force generated by a residual vibration of the actuator,or elastic wave generating device 106. A secondary mode is a secondaryfrequency of a waveform of a counter electromotive force generated by aresidual vibration of the actuator, or elastic wave generating device106. Because the frequency detected from the waveform of the counterelectromotive force generated by a residual vibration of the actuator106 substantially matches with the frequency of the maximum value of theadmittance characteristic measured by impedance analyzer, to measure thefrequency of the waveform of the counter electromotive force is equal toobtain the singular point of the acoustic impedance.

The patterns of numerical value for each combination of the primary moderesonant frequency and the secondary mode resonant frequency aredifferent by the difference of each residual quantity of ink in each ofink cartridges A, B, and C. Therefore, the residual quantity of inkcontained in the ink cartridge, which is mounted on the recordingapparatus, can be judged by measuring both the primary mode resonantfrequency and the secondary mode resonant frequency.

For example, as shown in FIG. 4, the patterns of the numerical value ofthe combinations of the primary mode resonant frequency and thesecondary mode resonant frequency are different for each of the inkcartridge A, ink cartridge B, and ink cartridge C, each of whichcontains a different residual quantity of ink. Therefore, the pattern ofnumerical value of the combination of the primary mode resonantfrequency and the secondary mode resonant frequency can be used as thepattern that shows the residual quantity of ink of the each inkcartridges.

The ink cartridge B has a pattern of peaks of primary mode and secondarymode resonant frequency which is shifted 100 kHz lower than the patternof peaks of primary mode and secondary mode resonant frequency of theink cartridge A. The ink cartridge C has a pattern of peaks of primarymode and secondary mode resonant frequency which is shifted 100 kHzhigher than the pattern of peaks of primary mode and secondary moderesonant frequency of the ink cartridge A. In this way, depends on theresidual quantity of ink contained in the ink cartridge, the pattern ofresonant frequency of the primary mode and secondary mode are different.Therefore, the residual quantity of ink contained in the ink cartridgecan be judged by detecting a resonant frequency of both of primary modeand secondary mode and recognizing the pattern of the combination of thenumerical value of the resonant frequency as the characteristic patternof the residual quantity of ink in the measured ink cartridge.

Here, the resonant frequency of the two modes, a primary mode and asecondary mode, are detected. However, residual quantity of ink can bejudged by detecting the resonant frequency of plurality of modes. Forexample, the residual quantity of ink can be judged by detecting theresonant frequency of two modes such as the primary mode and the thirdmode. Also, the residual quantity of ink can be judged by detecting theresonant frequency of two modes such as the secondary mode and the thirdmode.

FIG. 5(A) and FIG. 5(B) shows a waveform of the residual vibration ofthe actuator 106 and the measuring method of the residual vibration. Thechange of the ink level at the level of the mounting position of theactuator 106 in the ink cartridge can be detected by the change in thefrequency or the amplitude of the residual vibration remained after theoscillation of the actuator 106. In FIG. 5(A) and FIG. 5(B), thevertical axis shows the voltage of the counter electromotive forcegenerated by the residual vibration of the actuator 106, and thehorizontal axis shows the time. By the residual vibration of theactuator 106, the waveform of the analog signal of the voltage generatesas shown in FIG. 5(A) and FIG. 5(B). Then, the analog signal isconverted to a digital numerical value corresponding to the frequency ofthe signal.

In the example sown in FIG. 5(A) and FIG. 5(B), the existence of the inkis detected by measuring the time during the generation of the fournumbers of pulses from the fourth pulse to the eighth pulse of theanalog signal.

In detail, after the actuator 106 oscillates, the number of the timeswhen the analog signal get across the predetermined reference voltageform the low voltage side to the high voltage side. The digital signalis set to be high while the analog signal becomes fourth counts to theeighth counts, and the time during fourth counts to the eighth counts ismeasured by predetermined clock pulse.

FIG. 5(A) shows the waveform when the ink level is above the level ofthe mounting position of the actuator 106. FIG. 5(B) shows the waveformwhen the ink level is below the level of the mounting position of theactuator 106. Comparing the FIG. 5(A) and FIG. 5(B), the time of theFIG. 5(A) during the fourth counts to the eighth counts is longer thanthe time of the FIG. 5(B). In other words, depends on the existence ofthe ink, the time from the fourth counts to the eighth counts isdifferent. By using this difference of the time, the consumption statusof the ink can be detected. The reason to count the analog signal fromthe fourth counts is to start the measurement of the time after thevibration of the actuator 106 becomes stable. It is only one of theexample of starting the measurement from fourth counts, but measurementcan be started from the desired counts.

The signals from the fourth counts to the eighth counts are detected,and the time from the fourth counts to the eighth counts is measured bythe predetermined clock pulse. By this measurement, the resonantfrequency can be obtained. The clock pulse is prefer to be a pulsehaving a same clock with the clock for controlling such as thesemiconductor memory device which is mounted on the ink cartridge. Itdoes not necessary to measure the time until the eighth counts, but thetime until the desired counts can be measured. In FIG. 5, the time fromthe fourth counts to the eighth counts is measured, however, the timeduring the different interval of the counts also can be detectedaccording to the circuit configuration which detects the frequency.

For example, when the ink quality is stable and the fluctuation of theamplitude of the peak is small, the resonant frequency can be detectedby detecting the time from the fourth counts to the sixth counts toincrease the speed of detection. Moreover, when the ink quality isunstable and the fluctuation of the amplitude of the pulse is large, thetime from the fourth counts to the twelfth counts can be detected todetect the residual vibration accurately.

Furthermore, as other embodiments, the wave number of the voltagewaveform of the counter electromotive force during the predeterminedperiod can be counted. More specifically, after the actuator 106oscillates, the digital signal is set to be high during thepredetermined period, and the number of the times when the analog signalcrosses the predetermined reference voltage from the low voltage side tothe high voltage side is counted. By measuring the count number, theexistence of the ink can be detected.

Furthermore, it can be known by comparing FIG. 5(A) with FIG. 5(B), theamplitude of the waveform of the counter electromotive force isdifferent when the ink is filled in the ink cartridge and when the inkis not in the cartridge. Therefore, the ink consumption status in theink cartridge can be detected by measuring the amplitude of the waveformof the counter electromotive force without calculating the resonantfrequency. More specifically, for example, a reference voltage is setbetween the peak point of the waveform of the counter electromotiveforce of the FIG. 5(A) and the peak point of the waveform of the counterelectromotive force of the FIG. 5(B). Then, after the actuator 106oscillates, set the digital signal to be high at the predetermined time.Then, if the waveform of the counter electromotive force crosses thereference voltage, it can be judged that there is no ink in the inkcartridge. If the waveform of the counter electromotive force does notcrosses the reference voltage, it can be judged that there is ink in theink cartridge.

The residual vibration of the actuator 106 is preferably measured when acarriage is not moving or when a recording head is not printing. If theresidual vibration is measured when the recording head is printing,because a central processing unit (CPU) of the ink jet recordingapparatus is used for measuring the residual vibration, the time thatcan use a CPU for printing decreases and the printing speed thereforedecreases.

Therefore, by measuring the residual vibration when the recording headis not printing, which is the time that the CPU is not used forprinting, the decrease of the printing speed can be prevented.Furthermore, the case in which the ink container is the type, which ismounted on the carriage and moving together with carriage, will beconsidered. If the residual vibration is measured when the recordinghead is printing, the residual vibration cannot be accurately measuredbecause ink inside of the ink container rolls by the movement of the inkcontainer. Therefore, it is preferable to measure the residual vibrationwhen the recording head is not printing. Furthermore, when the recordinghead is not printing, the motor that drives the carriage is not moving,and the residual vibration thus can be measured with avoiding the noisegenerated during the driving of the recording head and the motor ofcarriage.

Therefore, the residual vibration can be measured more accurately. Thetiming when the recording head is not printing includes the timings suchas during the changing of the pages, during the cleaning of therecording head, at the time of switching-on the power supply, justbefore the switching-off the power supply, that is, the time from theswitching-off the power supply until the recording apparatus actuallystops.

FIG. 5(C) shows the example in which the time of the pulse wave from thefourth counts to the eighth counts is measured by predetermined clockpulse. In this figure, the clock pulse is arises for four counts duringthe fourth counts to the eighth counts. Actually, the clock pulse fromthe 100 counts to the 200 counts will arise, however, to make theexplanation simple, the small number of clock pulse will be used forexplanation. Because the clock pulse is a pulse having a constantperiod, the time can be measured by counting the number of clock pulse.The resonant frequency is obtained by measuring the time from the fourthcounts to the eighth counts. The clock pulse preferably has a periodwhich is shorter than the period of the waveform of the counterelectromotive force. For example, the clock pulse preferably has ahigher frequency such as 16 MHz.

FIG. 6 shows a configuration of the recording apparatus control unit2000 which detects a liquid consumption status inside the container 1 bydetecting a change of acoustic impedance using the actuator 106 andcontrols the ink jet recording apparatus based on the detected result.The recording apparatus control unit 2000 comprises a liquid consumptionstatus detecting unit 1200 and a control circuit unit 1500. The liquidconsumption status detecting unit 1200 provides the activating voltageto the actuator 106 mounted on the container 1 and detects the liquidconsumption status from the change of the acoustic impedance detected bythe actuator 106 as a result of activation. The control circuit unit1500 controls a recording apparatus based on the detected results of theliquid existence output by the liquid consumption status detecting unit1200.

The control circuit unit 1500 has a control unit 1400 and a recordingapparatus operation control unit 1402. The control unit 1400 controls arecording apparatus operation control unit 1402 based on the detectedresults of the liquid existence output by the liquid consumption statusdetecting unit 1200. The recording apparatus operation control unit 1402controls the operation of the recording apparatus based on the directionof the control unit 1400. The control circuit unit 1500 further has aindicating process unit 1404, a printing operation control unit 1406, anink supplementing process unit 1408, a cartridge exchanging process unit1410, a printing data storing process unit 1412, and a printing datastoring unit 1414, the operation of which are controlled by therecording apparatus operation control unit 1402.

The recording apparatus control unit 2000 may be provided inside of theink jet recording apparatus. A part of the function of the recordingapparatus control unit 2000 may be provided on the outside of therecording apparatus control unit 2000. For example, the function of thecontrol circuit unit 1500 may be provided to the outside apparatus suchas computer connected to the recording apparatus. Furthermore, a part ofthe function of the recording apparatus control unit 2000 may be storedin the recording medium as a program and supplied to the outsidecomputer. By supplying a part of the function of the recording apparatuscontrol unit 2000 as a program stored in the recording medium to thecomputer connected to the recording apparatus, the operation of therecording apparatus can be always controlled by the latest function byeasily storing the program, which performs the latest function, in therecording medium of the computer when a part of the function of therecording apparatus control unit 2000 is improved in the future.

Furthermore, a part of the function of the recording apparatus controlunit 2000 may be sent from the information processing apparatus such asa server to a terminal such as a computer connected to the recordingapparatus through an electric communication line as a program. In thiscase, by storing the latest function in the recording apparatus of acomputer which is easily sent from a server through an electriccommunication line, the recording apparatus can always perform thelatest function.

The liquid consumption status detecting unit 1200 activates the actuator106 and detects the existence of liquid in the container 1 from a changeof the acoustic impedance. For example, the liquid consumption statusdetecting unit 1200 has a measuring circuit unit 800, which measures acounter electromotive force such as the voltage value generated by theresidual vibration of the actuator 106, and a detecting circuit unit1100, which outputs the signal that shows the existence of liquid in thecontainer 1 by inputting the counter electromotive force measured by themeasuring circuit unit 800.

The measuring circuit unit 800 has an activating voltage generating unit850 which generates the activating voltage to activate the actuator 106.The actuator 106 mounted on the container 1 is activated and oscillatedby the activating voltage generated by the activating voltage generatingunit 850. The actuator 106 continues to vibrate residually after theoscillation, and the actuator 106 itself generates a counterelectromotive force by this residual vibration. The measuring circuitunit 800 further transforms the analog signal of the waveform of thecounter electromotive force generated by the actuator 106 to the digitalsignal which corresponds to the frequency of the waveform of the counterelectromotive force and outputs to the digital circuit unit 900.

The detecting circuit unit 1100 has a digital circuit unit 900, whichcounts the number of the pulse of the signal output by the measuringcircuit unit 800 during a constant time period digitally, and a liquidexistence judging unit 1000, which judges the existence of liquid basedon the number of the pulse counted by the digital circuit unit 900. Inthe present embodiment, the digital circuit unit 900 outputs the signalwhich is high from the fourth counts to the eighth counts in thewaveform of the counter electromotive force output by the digitalcircuit unit 900. Furthermore, as shown in FIG. 5(C), the digitalcircuit unit 900 counts the number of the pulse of the predeterminedclock pulse which has shorter period than the period of the waveform ofthe counter electromotive force during the period when the abovementioned digital signal is high from the fourth counts to the eighthcounts. By counting the number of the pulse of the clock pulse having aconstant period, the time during the fourth counts to the eighth countscan be measured. For example, in FIG. 5(C), there are five counts of theclock pulse, and the time can be calculated by multiplying the fivecounts by the period of the clock pulse. Here, the clock pulse of lowfrequency is used to make the explanation simple, however, the clockpulse of high frequency such as 16 MHz is practically used. The liquidexistence judging unit 1000 judges the existence of liquid in thecontainer 1 based on the count value output by the digital circuit unit900 and outputs the judging result to the control circuit unit 1500.

When the liquid consumption status detecting unit 1200 outputs thejudging result that there is no ink in the liquid container 1, thecontrol unit 1400 controls the recording apparatus operation controlunit 1402 to perform the predetermined low ink level correspondingprocess. The low ink level corresponding process is the process whichdetermines whether there is little ink remaining in the liquid container1 and stops or restrains the operation of the recording apparatus suchas inappropriate printing. The recording apparatus operation controlunit 1402 performs the low ink level corresponding process bycontrolling the operations of the indicating process unit 1404, theprinting operation control unit 1406, the ink supplementing process unit1408, the cartridge exchanging process unit 1410 or printing datastoring process unit 1412 based on the direction of the control unit1400.

The indicating process unit 1404 indicates the information correspondingto the actuator 106 that detects the existence of liquid in the liquidcontainer 1. To indicate the information, there are a method ofindicating by the display 1416 and a speaking by the speaker 1418. Thedisplay 1416 is, for example, display panel of the recording apparatusor the screen of the computer connected to the recording apparatus.Furthermore, the indicating process unit 1404 is connected to thespeaker 1418, and if the actuator 106 detects that there is no ink atthe mounting position of the actuator 106 in the liquid container 1, theindicating sound is output from the speaker 1418. The speaker 1418 canbe a speaker of the recording apparatus or a speaker of the outsideapparatus such as a computer connected to a recording apparatus.Moreover, voice signal also can be suitably used for indicating sound,and synthetic voice that indicates the ink consumption status can begenerated by the voice synthesizing process.

The printing operation control unit 1406 controls the printing operationunit 1420 to stop the printing operation of the recording apparatus. Bythe stopping of the printing process, the printing operation after therunning out ink can be avoided. Moreover, the printing operation controlunit 1406 can prohibit the printing process to move to the next printingprocess after finishing of the certain printing process as other exampleof the low ink level corresponding process. By this prohibiting of theprinting process, it is avoided that the one printing process, such asprinting of a series of sentence, is stopped on the halfway of printingprocess. Moreover, as an example of prohibiting the printing process, itis preferable to prohibit the printing process after the starting of thenew page to prevent the printing process to be stopped on the halfway ofprinting the one page.

The ink supplementing process unit 1408 controls the ink supplementingapparatus 1422 to supplement ink in the ink cartridge automatically. Bythis supplementing of ink, the printing operation can be continuedwithout interrupting. The cartridge exchanging process unit 1410controls the cartridge exchanging apparatus 1424 to exchange the inkcartridge automatically. This corresponding process also can continuethe printing operation without troubling the user. The printing datastoring process unit 1412 stores the printing data, which is the databefore the finishing of the printing, in the printing data storing unit1414 as a low ink level corresponding process. This printing data is thedata which is sent to the recording apparatus after the detection of theink-end. By this storing of the printing data, the loss of the printingdata before the printing can be avoided.

All these configurations from the 1404 to 1412 do not have to beprovided to the recording apparatus control unit 2000. Also, all of thelow ink level corresponding process does not have to be performed, andat least one of the low ink level corresponding processes can beperformed. For example, if the ink supplementing process unit 1408 orthe cartridge exchanging process unit 1410 performs the process, theprinting operation control unit 1406 does not have to prohibit theprinting operation. Furthermore, the recording apparatus control unit2000 can have a configuration that can perform the low ink levelcorresponding process other than the process explained above and have aconfiguration which can avoid the inappropriate printing operation bythe shortage of ink. Furthermore, the above mentioned low ink levelcorresponding process is preferable to be performed after the printingof the “predetermined quantity of allowance” after the actuator 106detects the non-ink status at the mounting position of the actuator 106.The “predetermined quantity of allowance” is set to be an appropriatevalue which is less than the printing quantity that consume all the inkafter the detection of no-ink status by the actuator 106.

FIG. 7 shows a block diagram of the other embodiment of the recordingapparatus control unit 2002. In the present embodiment, three actuators106A, 106B, and 106C are mounted on the liquid container 1. Threeactuators 106A, 106B, and 106C are mounted on the different position inthe direction along which the liquid decreases by the liquidconsumption. The measuring circuit unit 802 shown in FIG. 7 includesactivating voltage generating units 850A, 850B, and 850C, each of whichprovides the voltage that activates the actuator to each of actuators106A, 106B, and 106C which are mounted on the liquid container 1,respectively. The digital circuit unit 902 in the detecting circuit unit1102 inputs each of the counter electromotive force signals generated bythe actuators 106A, 106B, and 106C from the measuring circuit unit 802and counts the number of pulses within predetermined time range of eachof the counter electromotive force signals. Furthermore, the liquidexistence judging unit 1002 judges the existence of liquid in the liquidcontainer 1 based on each of the count value of the counterelectromotive force signal output from the digital circuit unit 902.Because each of a plurality of actuators is mounted on the differentpositions along the liquid decreasing direction in the presentembodiment, the liquid consumption status at each of the mountingpositions of the actuator can be detected step by step. Because theconfiguration of the recording apparatus control unit 2002 other thanthe liquid consumption status detecting unit 1202 is the same as theconfiguration of the recording apparatus control unit 2000 shown in FIG.6, the explanation of which will be omitted.

The output signal of the actuator is different and depends on whetherthe liquid level is higher or lower than the level of the mountingposition of the actuator. For example, the frequency or amplitude of thedetected counter electromotive force changes greatly, and the detectionsignal changes according to the changes of the frequency or amplitude ofthe counter electromotive force. The liquid consumption status detectingunit 1202 can judge whether the liquid level has been passed througheach level of the mounting position of the actuator 106A, 106B, and 106Cbased on the detection signal. The detection process is performedperiodically, at the previously determined timing.

Here, let the status where the liquid level is lower than the mountingposition of the actuator as the “no-liquid status”, and let the statuswhere the liquid level is higher that than the actuator as the“liquid-having status”. If the liquid level passes through the actuator,the detection result changes from “liquid-having status” to “no-liquidstatus”.

In the present embodiment, the detection of the liquid passing throughshows this change of the detection results.

As the characteristic of the present embodiment, the control unit 1400switches the actuator 106 used for detecting impedance in the directionalong which the level of the liquid surface decreases. In detail, justafter the mounting of the liquid container 1, that is, when the liquidis fully filled in the liquid container 1, only the actuator 106A isused for detection. If liquid is consumed and the liquid level passesthrough the actuator 106A, the actuator 106A detects the no-liquidstatus. Responding to this, the control unit 1400 switches the liquiddetection position to middle stage of the liquid container 1. That is,the liquid consumption is detected by using only the actuator 106B.Similarly, if the actuator 106B detects the no-liquid status, thedetection position is switched to the mounting position of the lowestactuator 106C.

According to the present embodiment, because the detection position isswitched downward sequentially, all the actuators 106 do not have tooperate all the time, and the frequency of the operation of the actuator106 decreases. Therefore, the quantity of data to be processed in thecontrol unit 1400 can be reduced. As a result, the detection processdoes not decrease the throughput of the printing operation.

In the present embodiment, the number of actuators is three. However,the numbers of actuators 106 can be any number if it is three or morethan three. Moreover, the interval of the mounting position of theactuator does not have to be constant. For example, it is preferable toarrange the interval of the actuators narrower as the liquid leveldecreases. The variation shown above can be similarly applied to thefollowing other embodiments.

FIG. 8 shows further other embodiment of the recording apparatus controlunit 2000 shown in FIG. 6. The liquid container 1 shown in FIG. 8 ismounted on a carriage so that the liquid in the liquid container 1 canbe communicated to a head 1300 which discharges the liquid in the liquidcontainer 1 to recording medium for printing. The head 1300 is driven bythe head driving unit 1440. The recording apparatus shown in FIG. 8 hasa cleaning unit 1436 which absorbs the liquid from the head 1300 toclean the nozzle of the head 1300. The cleaning unit 1436 absorbs theliquid from the head 1300 by driving the pump 1434 by the cleaningdriving unit 1432.

The control circuit unit 1502 of the recording apparatus control unit2000 shown in FIG. 8 not only has the element comprised in the recordingapparatus control unit 2000 shown in FIG. 6 but further has a liquiddischarging counter 1450, a liquid consumption quantity calculating unit1452, and a cleaning control unit 1442. The liquid discharging counter1450 counts the number of ink drops discharged from the head 1300. Theliquid consumption quantity calculating unit 1452 calculates thequantity of ink consumption based on the number of ink drops counted bythe liquid discharging counter 1450. The cleaning control unit 1442controls the cleaning driving unit 1432 based on the ink consumptionstatus detected by the liquid consumption status detecting unit 1210.Furthermore, the detecting circuit unit 1104 includes a liquidconsumption status correcting unit 1010 which corrects the number of inkdrops discharged from the head 1300 that is counted by the liquiddischarging counter 1450 based on the ink consumption status detected bythe actuator 106.

Next, the operation of the element newly added in FIG. 8 will beexplained. The liquid discharging counter 1450 counts the number of inkdrops discharged from the head 1300 during the printing and outputs tothe liquid consumption quantity calculating unit 1452. The liquidconsumption quantity calculating unit 1452 calculates the ink quantitydischarged from the head 1300 based on the count value of the liquiddischarging counter 1450. Furthermore, ink is also consumed by flushingoperation. The flushing operation recovers an uneven meniscus around thenozzle opening of the head 1300 and prevents the clogging of the ink inthe nozzle opening by discharging the ink drop idly by applying thedriving signal, which is not related to the printing operation, to head1300. Therefore, the liquid discharging counter 1450 also counts thenumber of the discharged ink drops by the flushing operation and outputsto the liquid consumption quantity calculating unit 1452. The liquidconsumption quantity calculating unit 1452 calculates the inkconsumption quantity from the number of ink drops discharged from thehead 1300 by the printing operation and the flushing operation andoutputs the calculated ink consumption quantity to the liquidconsumption status correcting unit 1010. The ink quantity calculated bythe liquid consumption quantity calculating unit 1452 is displayed bythe display 1416 of the indicating process unit 1404.

Furthermore, the ink in the liquid container 1 is also consumed byabsorbing ink in the head 1300 to clean the head 1300 by the cleaningunit 1436. Therefore, the liquid consumption quantity calculating unit1452 calculates the ink consumption quantity consumed by the cleaningoperation by multiplying the driving time of the pump 1434, which isdriven by the cleaning driving unit 1432, by the quantity of inkabsorbed by pump 1434 per time. The liquid consumption quantitycalculating unit 1452 inputs the driving time of the pump 1434 throughthe cleaning control unit 1442 from the cleaning driving unit 1432. Asan example of the driving time of the pump 1434, the time while theelectricity is supplied to the pump 1434 can be used.

Therefore, the liquid consumption quantity calculating unit 1452calculates the ink quantity by the liquid discharging counter 1450 andthe cleaning control unit 1442. The liquid consumption status correctingunit 1010 corrects the calculated value of the liquid consumptionquantity calculating unit 1452 based on the judging result of the liquidexistence judging unit 1000.

The reason for using three outputs from the liquid existence judgingunit 1000, the liquid consumption quantity calculating unit 1452, andthe cleaning control unit 1442 for detecting the ink consumption statuswill be explained in following. The output of the liquid existencejudging unit 1000 is the information which is obtained by actuallymeasuring the level of liquid surface at the mounting position of theactuator 106. On the other hand, the outputs of the liquid consumptionquantity calculating unit 1452 and the cleaning control unit 1442 areink consumption quantity which is estimated from the number of ink dropscounted by the liquid discharging counter 1450 and driving time of thepump 1434. This calculated value may cause an error because of thechanges of the form of printing of the user or the using environment,for example, changes of the pressure inside the ink cartridge or theviscosity of ink caused by extremes of room temperature or the timeelapsed after the ink cartridge has been unsealed. Therefore, the liquidconsumption status correcting unit 1010 corrects the ink consumptionquantity, which is calculated based on the output of the liquidconsumption quantity calculating unit 1452 and the cleaning control unit1442, with the judging result of the ink existence output from theliquid existence judging unit 1000. Furthermore, the liquid consumptionstatus correcting unit 1010 corrects the parameter of the equation usedby the liquid consumption quantity calculating unit 1452 for calculatingthe ink consumption quantity based on the judging result of the inkexistence output from the liquid existence judging unit 1000. Bycorrecting the parameter of equation, the equation is adapted to theenvironment in which the ink cartridge is used, so that the valueobtained from the equation can be close to the value which is actuallyused.

If the actuator 106 detects the no-ink status at the mounting position,the printing operation control unit 1406, the ink supplementing processunit 1408, the cartridge exchanging process unit 1410, the printing datastoring process unit 1412, and the cleaning control unit 1442, each ofwhich are controlled by the recording apparatus operation control unit1402, perform the predetermined low ink level corresponding process.

Because the printing operation control unit 1406 controls the headdriving unit 1440 to stop the discharging of the ink at the head 1300and reduce the quantity of discharging the ink, the printing operationafter the running out of ink can be avoided. The cleaning control unit1442 prohibits the cleaning operation, which cleans the head 1300 by thecleaning unit 1436, or reduce the number of times of cleaning or reducethe absorbing quantity of ink by reducing the power of the pump 1434 forabsorbing ink as a low ink level corresponding process. Comparativelylarge amount of ink is absorbed from the head 1300 during the cleaningof the head 1300. Therefore, by prohibiting the cleaning operation whenthe ink level becomes low in the ink cartridge, the absorbing of thesmall amount of remained ink from the head 1300 for the cleaning can beavoided, and thus the shortage of ink caused by the cleaning operationcan also be avoided. Furthermore, the number of times of cleaning can bereduced, and the absorbing power of the pump 1434 can be reduced as alow ink level corresponding process. Based on the residual quantity ofink in the liquid container 1, the control unit 1400 selects which lowink level corresponding process to be performed by the printingoperation control unit 1406 and the cleaning control unit 1442.

FIG. 9 shows another embodiment of the recording apparatus control unit2004 shown in FIG. 8. In this embodiment, a semiconductor memory device7 is mounted on the liquid container 1, and the recording apparatuscontrol unit 2006 has an information storing control circuit unit 1444.Other configuration is same as the recording apparatus control unit 2004shown in FIG. 8. Therefore, the elements which are not related to thesemiconductor memory device 7 and the information storing controlcircuit unit 1444 are omitted. The functions and advantages obtained bythe configuration that comprising the semiconductor memory device 7 andthe information storing control circuit unit 1444 will be explained infollowing as a characteristic of the present embodiment.

The liquid container 1 has an actuator 106 and a semiconductor memorydevice 7. The semiconductor memory device 7 is a memory which can berewritten such as EEPROM. The control circuit unit 1506 has aninformation storing control circuit unit 1444. The liquid consumptionstatus detecting unit 1210 detects the liquid consumption status in theliquid container 1 by controlling the actuator 106 and outputs theconsumption related information, which is related to the detection ofthe liquid consumption status using the actuator 106, to the controlcircuit unit 1506. The control unit 1400 writes the consumption relatedinformation into the semiconductor memory device 7 through theinformation storing control circuit unit 1444. Furthermore, theinformation storing control circuit unit 1444 reads the consumptionrelated information from the semiconductor memory device 7 and outputsto the control unit 1400.

Next, the semiconductor memory device 7 will be explained in detail. Thesemiconductor memory device 7 stores the consumption related informationwhich is related to the detection of the liquid consumption status usingthe actuator 106. The consumption related information includes theinformation of detected consumption status of ink. The informationstoring control circuit unit 1444 writes the consumption relatedinformation obtained by using the actuator 106 into the semiconductormemory device 7. Then, this consumption related information is read outfor used at the recording apparatus control unit 2006.

To store the consumption related information in the semiconductor memorydevice 7 is especially advantageous for the mounting and removing of theliquid container 1. The case is considered in which the liquid container1 is removed from the ink jet recording apparatus when the liquid isconsumed halfway. At this time, the semiconductor memory device 7, whichstores the consumption related information, is always together with theliquid container 1. The liquid container 1 is mounted on the same inkjet recording apparatus again or is mounted on another ink jet recordingapparatus. At this time, the consumption related information is read outfrom the semiconductor memory device 7, and the recording apparatuscontrol unit 2006 operates based on the consumption related information.For example, if the consumption related information such that the liquidcontainer 1 mounted on the ink jet recording apparatus is empty or hasonly a small amount of residual ink, this consumption relatedinformation will be conveyed to the user. In this way, the formerconsumption related information of the liquid container 1 can bereliably used.

The semiconductor memory device 7 may further store the liquidconsumption status calculated by the liquid consumption quantitycalculating unit 1452 based on the number of ink drop counted by theliquid discharging counter 1450. The actuator 106 can reliably detectsthe level of the liquid surface to be passed through the mountingposition of the actuator 106. Therefore, it is preferable to estimatethe ink consumption status, which is the status before and after theliquid level passing through the mounting position of the actuator, fromthe liquid consumption status calculated by the liquid consumptionquantity calculating unit 1452. This estimated value is stored in thesemiconductor memory device 7.

Moreover, the consumption related information includes the detectioncharacteristic information, which is to be detected according to theliquid consumption status. In the present embodiment, the detectioncharacteristic information before the consumption and the detectioncharacteristic information after the consumption are stored as thedetection characteristic information. The detection characteristicinformation before the consumption is the detection characteristicbefore the starting of the ink consumption, that is, the detectioncharacteristic at the ink-full status. The detection characteristicinformation after the consumption is the detection characteristicestimated to be detected when the ink is consumed to the predetermineddetection target, concretely, the detection characteristic when thelevel of the ink surface becomes lower than the level of the mountingposition of the actuator 106.

The information storing control circuit unit 1444 reads out thedetection characteristic information from the semiconductor memorydevice 7, and the liquid consumption status detecting unit 1210 detectsthe liquid consumption status using the actuator 106 based on thedetection characteristic information read out from the semiconductormemory device 7. If the detection signal corresponded to the detectioncharacteristic information before the consumption is obtained, it can beconsidered that the consumption of liquid is not progressed, and thereis large amount of residual ink. At least, it can be reliably known thatthe level of ink surface is above the mounting position of the actuator106. On the other hand, if the detection signal corresponded to thedetection characteristic information after the consumption is obtained,it can be considered that the consumption of liquid is progressed, andthere is small amount of residual ink. Therefore, it can be known thatthe level of ink surface is below the mounting position of the actuator106.

One of the advantages to store the detection characteristic informationin the semiconductor memory device 7 will be explained. The detectioncharacteristic information is determined by a various kinds of factorsuch as a shape of the liquid container 1, a specification of actuator106, and a specification of ink. If there is a change in design such asimprovement of design, the detection characteristic may also change. Ifthe liquid consumption status detecting unit 1210 always uses the samedetection characteristic information, it is not easy to deal with thechange of these detection characteristic. Because the present embodimentstores and uses the detection characteristic information in thesemiconductor memory device 7, the present embodiment can easily dealwith the change of the detection characteristic information. Of course,even in the case that the liquid container 1 of new specification isprovided, the recording apparatus control unit 2000 can easily use thedetection characteristic information of the liquid container 1.

Further preferably, the detection characteristic information for each ofthe liquid containers 1 are measured and stored in the semiconductormemory device 7. Even the specification of the liquid containers 1 aresame, each of the detection characteristic information may be differentbecause of the unevenness of manufacturing. For example, there is casethat the detection characteristic information is different according tothe shape and thickness of the liquid container 1. Because each of theliquid containers 1 includes the semiconductor memory device 7 in thepresent embodiment, the detection characteristic informationcharacteristic for each of the liquid container 1 can be stored in thesemiconductor memory device 7. Therefore, the influence of theunevenness of manufacturing on the detection can be reduced, and theaccuracy of detection can be improved. In this way, the presentembodiment is advantageous for the difference of the detectioncharacteristic for each of the liquid container 1.

FIG. 10 shows a flow chart of the operation process of the recordingapparatus control unit 2006. First, it is judged whether the inkcartridge is mounted on the recording apparatus (S10). It is detectedthat the ink cartridge, which is new or used halfway, is mounted. Thisprocess is performed by using the element such as the switch, not shownin the figure, comprised in the ink jet recording apparatus. If the inkcartridge is mounted on the recording apparatus, the consumption relatedinformation including the detection characteristic information is readout from the semiconductor memory device 7 (S12). The indicating processunit 1404, the printing operation control unit 1406, the inksupplementing process unit 1408, the cartridge exchanging process unit1410, the printing data storing process unit 1412, and the cleaningcontrol unit 1442 of the recording apparatus control unit 2006 use theconsumption related information which is read out from the semiconductormemory device 7. For example, if it is known that there is only smallamount of residual liquid in the liquid container 1 from the consumptionrelated information read out from the semiconductor memory device 7, thedisplay 1416 displays that there is only small amount of residualliquid, and stops the movement of the head 1300.

The liquid consumption status detecting unit 1210 detects the liquidconsumption status using the actuator 106 based on the detectioncharacteristic information read out from the semiconductor memory device7 (S14). Next, the existence of the liquid in the liquid container 1 isjudged base on the detected liquid consumption status (S16). If theno-ink status is detected, the no-ink corresponding means (S18) isperformed. As an example of the no-ink corresponding means (S18), thesteps such as a step of storing the printing data by the printing datastoring process unit 1412 (S24), a step of stopping the printingoperation by the printing operation control unit 1406 (S26), and a stepof indicating a no-ink status by the indicating process unit 1404 (S28)are included. In this case, ink is supplemented to the ink jet recordingapparatus, which is performed by user to exchange the ink cartridgeaccording to the direction of the no-ink indicating step (S28).

Moreover, an ink cartridge can be exchanged automatically by thecartridge exchanging process unit 1410 (S20), and ink can besupplemented automatically by the ink supplementing process unit 1408(S22) as a no-ink corresponding means step (S18). In this case, ink isautomatically supplemented to the ink jet recording apparatus, andbecause user does not have to exchange the ink cartridge, the process isfeedback to the liquid consumption information read out process withoutthrough the cartridge exchanging judging step (S32). In case of the inksupplementing step (S22), the information of how much quantity of ink issupplemented to the recording apparatus is stored in the semiconductormemory device 7 after the supplement of ink.

After the performing of the printing data storing step (S24), printingoperation stopping step (S26), and no-ink indicating step (S28) as anno-ink corresponding means (S18), the detected liquid consumption statusis stored in the semiconductor memory device 7 (S30). Then, because theinformation that there is no-ink in the ink cartridge is conveyed touser by the no-ink indicating step (S28), if user exchanges the inkcartridge (S32, Y) according to the direction of the no-ink indicatingstep (S28), the process feeds back to the liquid consumption statusdetecting step (S14). On the other hand, if user does not exchange theink cartridge, the indication, which indicates user to exchange the inkcartridge, is indicated by the display or speaker, and then theoperation process of the recording apparatus control unit 2006 is end.

FIG. 11 shows a circuit configuration of the measuring circuit unit 800.The measuring circuit unit 800 has a activating voltage generating unit850, a reference voltage generating unit 816, a high pass filter 824, aamplifying unit 860, and a comparator 836. The activating voltagegenerating unit 850 includes two bipolar transistors of a NPN typetransistor 810 and a PNP type transistor 812. A base B of the NPN typetransistor 810 and a base B of the PNP type transistor 812 are connectedwith each other in parallel complementary. An emitter E of the NPN typetransistor 810 and an emitter E of the PNP type transistor 812 are alsoconnected with each other in parallel complementary. The NPN typetransistor 810 and the PNP type transistor 812 are the transistors thatactivate the actuator 106. One of the terminal of the actuator 106 isconnected to the emitter E of which the NPN type transistor 810 and thePNP type transistor 812 is connected each other, and the anotherterminal of the actuator 106 is connected to the ground GND. The anotherterminal of the actuator 106 can be connected to the power source Vcc.

A trigger signal, which is input to the activating voltage generatingunit 850 from a terminal 840, rises to High signal from Low signal, thebase B of the NPN type transistor 810 and the base B of the PNP typetransistor 812 connected each other are rising up. Then the NPN typetransistor 810 and the PNP type transistor 812 amplifies the current ofthe input trigger signal and provides to the actuator 106. In FIG. 11,the voltage between the emitter E and the collector C of the PNP typetransistor 812 is provided to the actuator 106. Therefore, the actuator106 is charged rapidly and oscillates. Furthermore, the actuator 106generates a counter electromotive force by the residual vibration of theactuator 106 itself that is remained after the oscillation of theactuator 106. The counter electromotive force generated by the residualvibration of the actuator 106 is output to the amplifying unit 860through the high pass filter 824.

The connections between the base B and the emitter E of the NPN typetransistor 810 and the PNP type transistor 812 are PN junction.Therefore, the current substantially does not flow at emitter E when thepotential difference between the base B and the emitter E is 0.6 V orlower than 0.6V, and the current that is greatly amplified flows atemitter E when the potential difference exceeds 0.6 V. Because each ofthe NPN type transistor 810 and the PNP type transistor 812 has a 0.6 Vof dead band or bias voltage, the NPN type transistor 810 and the PNPtype transistor 812 has a bias voltage of about sum of 1.2 V. If theelectric potential of the terminal including counter electromotive forceof the actuator 106 is within the range of the dead band, thetransistors do not operate. Therefore, the operation of transistors doesnot suppress the residual vibration of the actuator 106. If thetransistors do not have dead band, the voltage of the actuator 106 iscontrolled by the transistors to be a constant value so that the counterelectromotive force cannot be measured.

In FIG. 11, a bipolar transistor is used for the NPN type transistor 810and the PNP type transistor 812, however, a field effect transistor,FET, can be used instead of a bipolar transistor. If using a fieldeffect transistor, an N-type field effect transistor is arranged at theposition where the NPN type transistor is arranged in FIG. 11. The gateof the N-type field effect transistor is arranged at the position of thebase B of the NPN type transistor 810, and source of the N-type fieldeffect transistor is arranged at the position of the emitter E of theNPN type transistor 810. Furthermore, a P-type field effect transistoris arranged at the position where the PNP type transistor 812 isarranged. The gate of the P-type field effect transistor is arranged atthe position of the base B of the PNP type transistor 812, and source ofthe P-type field effect transistor is arranged at the position of theemitter E of the PNP type transistor 812. Furthermore, the gates of theP-type field effect transistor and the N-type field effect transistorare connected each other, and the sources of the P-type field effecttransistor and the N-type field effect transistor are connected eachother. One of the terminal of the actuator 106 is preferable toconnected to the sources of the P-type field effect transistor andN-type field effect transistor which are connected each other, andanother terminal of the actuator 106 is preferable to connected to thepower source Vcc or ground GND.

The high pass filter 824 has a capacitor 826 and a resistor 818. Theoutput of the activating voltage generating unit 850 is output to theamplifying unit 860 through the high pass filter 824. The high passfilter 824 removes the low frequency components in the output of theactuator 106 and outputs the high frequency components in the output ofthe actuator 106 to the amplifying unit 860. Furthermore, the high passfilter 824 has a role to restrain the output of the amplifying unit 860to fall within a range from 0 V to 5 V from the reference electricpotential as a center. The reference voltage generating unit 816 has aresistor 818 and a resistor 820 connected together in series and acapacitor 822 which is connected to the resistor 820 in parallel. Thereference voltage generating unit 816 generates a stable direct currentelectric potential ranges from 2 V to 3 V as a reference electricpotential and provides to the high pass filter 824, the amplifying unit860, and the comparator 836. Therefore, the voltage of the waveform ofthe signal output from the high pass filter 824 and the amplifying unit860 vibrates around the reference electric potential as a center.

The amplifying unit 860 has an operational amplifier 834 and a resistor830 and 832. The operational amplifier 834 and the resistor 818 and 832are constructed to be a non-inverting amplifier which amplifies an inputsignal and outputs the input signal without inverting. The amplifyingunit 860 inputs the counter electromotive force signal output from theactivating voltage generating unit 850 to the plus terminal of theoperational amplifier 834 through the high pass filter 824. The minusterminal of the operational amplifier 834 of the amplifying unit 860 isconnected to the output of the operational amplifier 834 through thenegative feed back resistor 830 and further connected to the referenceelectric potential through the resistor 832. The operational amplifier834 amplifies the faint counter electromotive force signal, which isoutput from the actuator 106, based on the reference electric potentialas center. The waveform of this amplified counter electromotive forcesignal is shown as analog waveform shown in FIG. 5.

The comparator 836 inputs the voltage of the counter electromotive forcesignal output from the amplifying unit 860 and the reference electricpotential output from the reference voltage generating unit 816 andgenerates the counter electromotive force signal having a digitalwaveform by outputting High signal when the voltage of the counterelectromotive force signal is higher than the reference electricpotential and outputting a Low signal when the voltage of the counterelectromotive force signal is lower than the reference electricpotential. Because the output of the operational amplifier 834 vibratesaround the reference electric potential as center, and the voltage atthe minus terminal of the comparator 836 is equivalent to the referenceelectric potential, the comparator 836 compares the voltage of thecounter electromotive force signal with the reference electric potentialas reference and outputs the counter electromotive force signal having adigital waveform. The comparator 836 outputs the generated counterelectromotive force signal having a digital waveform to the terminal844.

FIG. 12 shows a circuit configuration of the detecting circuit unit1100. The detecting circuit unit 1100 has a digital circuit unit 900 anda liquid existence judging unit 1000. The digital circuit unit 900includes a flip flop 910 and 918, a counter 912 and 920, and an NANDgate 914 and 916. It is assumed that the counter 920 maintains maximumvalue even if the clock pulse is input to the counter 920 after thecounter 912 counts the maximum value (1111, 1111).

When the trigger signal is input to the clock input pin CLK of the flipflop 910 from the terminal 842, the flip flop 910 outputs a signal whichcontrols the counter 912 to start the measuring the pulse number of thecounter electromotive force signal output from the measuring circuitunit 800 to the counter 912. Furthermore, if the counter 912 countseight numbers of the pulse of the counter electromotive force signal,the counter 912 clears the flip flop 910 through the NAND gate 916.Therefore, the flip flop 910 starts providing the High signal to thecount enable terminal ENP of the counter 912 when the trigger signal isinput to the flip flop 910 and stops providing the High signal when theeight pulses of the counter electromotive force signal is counted by thecounter 912. The counter 912 counts the clock only when the signal inputthe count enable terminal ENP is High. The counter 912 starts countingthe pulse number of the counter electromotive force signal when thetrigger signal is input to the flip flop 910 and ends counting the pulsenumber when counting eight numbers of pulses because the signal input tothe count enable terminal ENP becomes Low. The counter 912 outputs thesignal, which is High from the fourth pulse to the eighth pulse, formthe output pin QC to the input pin D of the flip flop 918.

The flip flop 918 inputs the signal, which is High from the fourth pulseto the eighth pulse output from the counter 912, from the input pin D,and inputs a clock having a frequency of 16 MHz, which is input from theterminal 846, from a clock input pin CLK. Then, the flip flop 918synchronizes the signal input from the input pin D with the clock inputfrom the clock input pin CLK and outputs the synchronized signal. Thecounter 920 inputs the same clock pulse with the clock pulse input tothe flip flop 918 having frequency of 16 MHz from the clock input pinCLK. Therefore, the counter 920 operates with synchronizing with theflip flop 918 so that the counter 920 can counts the pulse number of 16MHz clock pulse while the output of the output pin/Q of the flip flop910 is High from the fourth pulse to the eighth pulse. By counting thepulse number of the 16 MHz clock pulse, the time during the four numbersof pulses arise from the fourth pulse to the eighth pulse can bemeasured. The flip flop 920 outputs the counted value to the liquidexistence judging unit 1000. The counter 920 is cleared before theoutput pin Q of the flip flop 918 becomes High, in other words, beforethe operating of the counter 920 because the output of the output pin/Qof the flip flop 918 and the output of the output pin QB of the counter912 are NAND operated at the NAND gate 914 and input to the clear inputpin CLR of the counter 920.

In FIG. 12, the pulse number of the 16 MHz clock pulse existed while thefourth pulse to the eighth pulse of the counter electromotive force iscounted. However, by using the output of the counter 912 and adding andcombining the counting circuit, not only the time until the eighth countbut also the time until the desired count can be counted. Therefore, thetime during the different count interval can be detected.

FIG. 13 shows a detailed circuit configuration of the liquid existencejudging unit 1000 shown in FIG. 12. The liquid existence judging unit1000 judges the existence of liquid in the liquid container 1 based onthe count value of the number of the 16 MHz clock pulse which arisesduring the fourth pulse to the eighth pulse of the counter electromotiveforce signal output by the counter 920. The liquid existence judgingunit 1000 has a maximum value resistor 1011, a minimum value resistor1012, a comparing unit 1014 and 1016, and AND gate 1018. The maximumvalue of the count value is stored in the maximum value resistor 1011,and minimum value of the count value is stored in the minimum valueresistor 1012.

The comparing unit 1014 inputs the count value output from the digitalcircuit unit 900 to a B terminal and inputs the maximum value of thecount value from the maximum value resistor 1011 to an A terminal. Ifthe count value is less than the maximum value, the comparing unit 1014outputs High signal to the AND gate 1018. On the other hand, if thecount value is the maximum value or over, the comparing unit 1014outputs Low signal to the AND gate 1018. When the count value is themaximum value or over, the frequency of the waveform of the counterelectromotive force is lower than the minimum value. Because thewaveform of the counter electromotive force is not measured normally,there is possibility that the liquid container is not mounted on therecording apparatus or not mounted on the recording apparatus reliably.

The comparing unit 1016 inputs the count value output from the digitalcircuit unit 900 to an A terminal and inputs the minimum value of thecount value from the minimum value resistor 1012 to an B terminal. Ifthe count value is larger than the minimum value, the comparing unit1016 outputs High signal to the AND gate 1018 and a terminal 1022. Onthe other hand, if the count value is the minimum value or under, thecomparing unit 1016 outputs Low signal to the AND gate 1018 and theterminal 1022. When the count value is minimum value or under, liquid inthe liquid container 1 is not existed at the mounting position of theactuator 106.

If both of the comparing unit 1014 and the comparing unit 1016 outputshigh signal, that is, the count value is less than the maximum value andlarger than the minimum value, the AND gate 1018 outputs High signal. Inthis case, because the frequency of the waveform of the counterelectromotive force is less than the maximum value, liquid in the liquidcontainer 1 existed at the mounting position of the actuator 106.Furthermore, because the frequency of the waveform of the counterelectromotive force is higher than the minimum value, it is known thatliquid in the liquid container 1 is in normal status in which the liquidcontainer 1 is reliably mounted on the recording apparatus and liquidexists at the level of the mounting position of the actuator 106. Thatis, if the terminal 1020 is High, liquid in the liquid container 1 is innormal status in which the liquid container 1 is reliably mounted on therecording apparatus, and liquid exists at the level of the mountingposition of the actuator 106.

If the comparing unit 1014 outputs Low signal and the outputs Highsignal, that is, the count value is the maximum value or over and morethan the minimum value, the AND gate 1018 outputs Low signal. Moreover,High signal is input to the terminal 1022. In this case, because theterminal 1020 is Low, liquid in the liquid container 1 is in abnormalstatus, and because the terminal 1022 is High, it can be judged that theliquid container 1 is not mounted on the recording apparatus or notreliably mounted on the recording apparatus.

FIG. 14 shows the manufacturing method of the actuator 106. A pluralityof the actuators 106, four numbers in the case of the FIG. 14, areformed as one body. The actuator 106 shown in FIG. 15 is manufactured bycutting the plurality of actuator 106, which is formed in one body asshown in FIG. 14, at each of the actuator 106. If the each of thepiezoelectric elements of the each of the plurality of the actuator 106,which is formed in one body as shown in FIG. 14, are circular shape, theactuator 106 shown in FIG. 1 can be manufactured by cutting the actuator106, which is formed as one body, at each of actuator 106. By forming aplurality of the actuator 106 in one body, a plurality of actuator 106can be manufactured effectively at the same time, and also the handlingduring the transportation becomes easy.

The actuator 106 has a thin plate or a vibrating plate 176, a base plate178, an elastic wave generating device or piezoelectric element 174, aterminal forming member or an upper electrode terminal 168, and aterminal forming member or a lower electrode terminal 170. Thepiezoelectric element 174 includes a piezoelectric vibrating plate or apiezoelectric layer 160, an upper electrode 164, and a lower electrode166. The vibrating plate 176 is formed on the top surface of the baseplate 178, and the lower electrode 166 is formed on the top surface ofthe vibrating plate 176. The piezoelectric layer 160 is formed on thetop surface of the lower electrode 166, and the upper electrode 164 isformed on the top surface of the piezoelectric layer 160. Therefore, themain portion of the piezoelectric layer 160 is formed by sandwiching themain portion of the piezoelectric layer 160 by the main portion of theupper electrode 164 and the main portion of the lower electrode 166 fromtop side and from bottom side.

A plurality of the piezoelectric element 174, four numbers in the caseof FIG. 14, is formed on the vibrating plate 176. The lower electrode166 is formed on the top surface of the vibrating plate 176. Thepiezoelectric layer 160 is formed on the top surface of the lowerelectrode 166, and the upper electrode 164 is formed on the top surfaceof the piezoelectric layer 160. The upper electrode terminal 168 and thelower electrode terminal 170 are formed on the end portion of the upperelectrode 164 and the lower electrode 166. The four numbers of theactuator 106 are used separately by cutting each of the actuator 106separately.

FIG. 15 shows a cross-section of a part of the actuator 106 shown inFIG. 15. The through hole 178a is formed on the face of the base plate178 which faces with the piezoelectric element 174. The through hole178a is sealed by the vibrating plate 176. The vibrating plate 176 isformed by the material which has electric insulating characteristic suchas alumina and zirconium oxide and also possible to be deformedelastically. The piezoelectric element 174 is formed on the vibratingplate 176 to face with the through hole 178 a. The lower electrode 166is formed on the surface of the vibrating plate 176 so as to be extendedto the one direction, left direction in FIG. 16, from the region of thethrough hole 178 a. The upper electrode 164 is formed on the surface ofthe piezoelectric layer 160 so as to be extended to the oppositedirection of the lower electrode 166, which is right direction in FIG.16, from the region of the through hole 178 a. Each of the upperelectrode terminal 168 and the lower electrode terminal 170 is formed onthe surface of the each of supplementary electrode 172 and the lowerelectrode 166, respectively. The lower electrode terminal 170 with thelower electrode 166 electrically, and the upper electrode terminal 168contacts with the upper electrode 164 electrically through thesupplementary electrode 172 to deliver a signal between thepiezoelectric element and the outside of the actuator 106. The upperelectrode terminal 168 and the lower electrode terminal 170 has a heighthigher than the height of the piezoelectric element which is the sum ofthe height of the electrodes and the piezoelectric layer.

FIG. 17 shows the manufacturing method of the actuator 106 shown in FIG.14. First, a through hole 940 a is formed on a green sheet 940 byperforating the green sheet 940 by a press or laser processing. Thegreen sheet 940 becomes the base plate 178 after the burning process.The green sheet 940 is formed by the material such as ceramic material.Then, a green sheet 941 is laminated on the surface of the green sheet940. The green sheet 941 becomes the vibrating plate 176 after theburning process. The green sheet 941 is formed by the material such aszirconium oxide. Then, a conductive layer 942, the piezoelectric layer160, and a conductive layer 944 is formed on the surface of the greensheet 941 sequentially by the method such as printing. The conductivelayer 942 becomes the lower electrode 166, and the conductive layer 944becomes the upper electrode 164 after the burning process. Next, thegreen sheet 940, the green sheet 941, the conductive layer 942, thepiezoelectric layer 160, and the conductive layer 944 are dried andburned. The spacer member 947 and 948 are provided on the green sheet941 to raising the height of the upper electrode terminal 168 and thelower electrode terminal 170 to be higher than the piezoelectricelement. The spacer member 947 and 948 is formed by printing the samematerial with the green sheet 940 and 941 or by laminating the greensheet on the green sheet 941. By this spacer member 947 and 948, thequantity of the material of the upper electrode terminal 168 and thelower electrode terminal 170, which is a noble metal, can be reduced.Moreover, because the thickness of the upper electrode terminal 168 andthe lower electrode terminal 170 can be reduced, the upper electrodeterminal 168 and the lower electrode terminal 170 can be accuratelyprinted to be a stable height.

If a connection part 944′, which is connected with the conductive layer944, and the spacer member 947 and 948 are formed at the same time whenthe conductive layer 942 is formed, the upper electrode terminal 168 andthe lower electrode terminal 170 can be easily formed and firmly fixed.Finally, the upper electrode terminal 168 and the lower electrodeterminal 170 are formed on the end region of the conductive layer 942and the conductive layer 944. During the forming of the upper electrodeterminal 168 and the lower electrode terminal 170, the upper electrodeterminal 168 and the lower electrode terminal 170 are formed to beconnected with the piezoelectric layer 160 electrically.

FIG. 18 shows further other embodiment of the ink cartridge of thepresent invention. FIG. 18(A) is a cross sectional view of the bottompart of the ink cartridge of the present embodiment. The ink cartridgeof the present embodiment has a through hole 1 c on the bottom face laof the container 1, which contains ink. The bottom part of the throughhole 1 c is closed by the actuator 650 and forms an ink storing part.

FIG. 18(B) shows a detailed cross section of the actuator 650 and thethrough hole 1 c shown in FIG. 18(A). FIG. 18(C) shows a plan view ofthe actuator 650 and the through hole 1 c shown in FIG. 18(B). Theactuator 650 has a vibrating plate 72 and a piezoelectric element 73which is fixed to the vibrating plate 72. The actuator 650 is fixed tothe bottom face of the container 1 such that the piezoelectric element73 can face to the through hole 1 c through the vibrating plate 72 andthe base plate 72. The vibrating plate 72 can be elastically deformedand is ink resistant.

Amplitude and frequency of the counter electromotive force generated bythe residual vibration of the piezoelectric element 73 and the vibratingplate 72 changes with the ink quantity in the container 1. The throughhole 1 c is formed on the position which is faced to actuator 650, andthe minimum constant amount of ink is secured in the through hole 1 c.Therefore, the status of the end of ink end can be reliably detected bypreviously measuring the characteristic of the vibration of the actuator650, which is determined by the ink quantity secured in the through hole1 c.

FIG. 19 shows other embodiment of the through hole 1 c. In each of FIGS.19(A), (B), and (C), the left hand side of the figure shows the statusthat there is no ink K in the through hole 1 c, and the right hand sideof the figure shows the status that ink K is remained in the throughhole 1 c. In the embodiment of FIG. 18, the side face of the throughhole 1 c is formed as the vertical wall. In FIG. 19(A), the side face 1d of the through hole 1 c is slanted in vertical direction and openswith expanding to the outside. In FIG. 19(B), a stepped portion 1 e and1 f are formed on the side face of the through hole 1 c. The steppedportion 1 f, which is provided above the stepped portion 1 e, is widerthan the stepped portion 1 e. In FIG. 19(C), the through hole 1 c has agroove 1 g that extends to the direction in which ink is easilydischarged, that is, the direction to a ink supply port 2.

According to the shape of the through hole 1 c shown in FIGS. 19(A) to19(C), the quantity of ink K in the ink storing part can be reduced.Therefore, because the M′cav can be smaller than the M′max explained inFIG. 1 and FIG. 2, the vibration characteristic of the actuator 650 atthe time of the ink end status can be greatly different with thevibration characteristic when enough quantity of ink K for printing isremained in the container 1, and thus the ink end status can be reliablydetected.

FIG. 20 shows a slant view of the other embodiment of the actuator. Theactuator 660 has packing 76 on the outside of the base plate, whichconstitutes the actuator 660, or the through hole 1 c of a mountingplate 72. Caulking holes 77 are formed on the outskirts of the actuator660. The actuator 660 is fixed to the container 1 through the caulkinghole 77 with caulking.

FIGS. 21(A) and 21(B) is a slant view of the further other embodiment ofthe actuator. In this embodiment, the actuator 670 comprises a concavepart forming base plate 80 and a piezoelectric element 82. The concavepart 81 is formed on the one side of the face of the concave partforming base plate 80 by the technique such as etching, andpiezoelectric element 82 is mounted on the other side of the face of theconcave part forming base plate 80. The bottom portion of the concavepart 81 operates as a vibrating region within the concave part formingbase plate 80. Therefore, the vibrating region of the actuator 670 isdetermined by the periphery of the concave part 81. Furthermore, theactuator 670 has the similar structure with the structure of theactuator 106 shown in FIG. 1, in which the base plate 178 and thevibrating plate 176 is formed as one body. Therefore, the manufacturingprocess during the manufacturing an ink cartridge can be reduced, andthe cost for manufacturing an ink cartridge also can be reduced. Theactuator 670 has a size which can be embedded into the through hole 1 cprovided on the container 1. By this embedding process, the concave part81 can operates as the cavity. The actuator 106 shown in FIG. 1 can beformed to be embedded into through hole 1 c as actuator 670 shown inFIG. 21.

FIG. 22 shows a slant view of the configuration that forms the actuator106 in one body as a mounting module 100. The module 100 is mounted onthe predetermined position of the container 1 of an ink cartridge. Themodule 100 is constituted to detect the ink consumption status in thecontainer 1 by detecting at least the change of acoustic impedance ofthe ink liquid. The module 100 of the present embodiment has a liquidcontainer mounting member 101 for mounting the actuator 106 to thecontainer 1. The liquid container mounting member 101 has a structurewhich mounts a cylindrical part 116 that contains the actuator 106 whichoscillates by the driving signal on a base mount 102, the plan of whichis substantially rectangular. Because the module 100 is constructed sothat the actuator 106 of the module 100 can not be contact from outsidewhen the module 100 is mounted on the ink cartridge, the actuator 106can be protected from outside contact. The top side of the edge of thecylindrical part 116 is chamfered so that the cylindrical part 116 canbe easily fit into the hole which is formed in the ink cartridge.

FIG. 23 shows an exploded view of the module 100 shown in FIG. 22 toshow the structure of the module 100. The module 100 includes a liquidcontainer mounting member 101 made from a resin and a piezoelectricdevice mounting member 105 which has a plate 110 and a concave part 113.Furthermore, the module 100 has a lead wire 104 a and 104 b, actuator106, and a film 108. Preferably, the plate 110 is made from a materialwhich is difficult to be rust such as stainless or stainless alloy. Theopening 114 is formed on the central part of the cylindrical part 116and the base mount 102 which are included in the liquid containermounting member 101 so that the cylindrical part 116 and the base mount102 can contain the lead wire 104 a and 104 b. The concave part 113 isformed on the central part of the cylindrical part 116 and the basemount 102 so that the cylindrical part 116 and the base mount 102 cancontain the actuator 106, the film 108, and the plate 110. The actuator106 is connected to the plate 110 through the film 108, and the plate110 and the actuator 106 are fixed to the liquid container mountingmember 101. Therefore, the lead wire 104 a and 104 b, the actuator 106,the film 108 and the plate 110 are mounted on the liquid containermounting member 101 as one body. Each of the lead wire 104 a and 104 btransfer a driving signal to piezoelectric layer by coupling with theupper electrode and the lower electrode 166 of the actuator 106, andalso transfer the signal of resonant frequency detected by the actuator106 to recording apparatus. The actuator 106 oscillates temporally basedon the driving signal transferred from the lead wire 104 a and 104 b.The actuator 106 vibrates residually after the oscillation and generatesa counter electromotive force by the residual vibration. By detectingthe vibrating period of the waveform of the counter electromotive force,the resonant frequency corresponding to the consumption status of theliquid in the liquid container can be detected. The film 108 bonds theactuator 106 and the plate 110 to seal the actuator 106. The film 108 ispreferably formed by such as polyolefin and bonded to the actuator 106and the plate 110 by heat sealing. By bonding the actuator 106 and theplate 110 with the film 108 face with face, the unevenness of thebonding on location decreases, and thus the portion other than thevibrating plate does not vibrate. Therefore, the change of the resonantfrequency before and after bonding the actuator 106 to plate 110 issmall.

The plate 110 is circular shape, and the opening 114 of the base mount102 is formed in cylindrical shape. The actuator 106 and the film 108are formed in rectangular shape. The lead wire 104, the actuator 106,the film 108, and the plate 110 can be attached to and removed from thebase mount 102. Each of the base mount 102, the lead wire 104, theactuator 106, the film 108, and the plate 110 is arranged symmetric withrespect to the central axis of the module 100. Furthermore, each of thecenters of the base mount 102, the actuator 106, the film 108, and theplate 110 is arranged substantially on the central axis of the module100.

The opening 114 of the base mount 102 is formed such that the area ofthe opening 114 is larger than the area of the vibrating region of theactuator 106. The through hole 112 is formed on the center of the plate110 where the vibrating section of the actuator 106 faces. As shown inFIG. 1 and FIG. 2, the cavity 162 is formed on the actuator 106, andboth of the through holes 112 and the cavity 162 forms ink storing part.The thickness of the plate 110 is preferably smaller than diameter ofthe through hole 112 to reduce the influence of the residual ink. Forexample, the depth of the through hole 112 is preferably smaller thanone third of the diameter of the through hole 112. The shape of thethrough hole 112 is substantially true circle and symmetric with respectto the central axis of the module 100. Furthermore, the area of thethrough hole 112 is larger than the area of opening of the cavity 162 ofthe actuator 106. The periphery of the shape of the cross-section of thethrough hole 112 can be tapered shape of stepped shape. The module 100is mounted on the side, top, or bottom of the container 1 such that thethrough hole 112 faces to the inside of the container 1. When the ink isconsumed, and the ink around the actuator 106 is exhausted, the resonantfrequency of the actuator 106 greatly changes. The change of the inklevel can thus be detected.

FIG. 24 shows the slant view of the other embodiments of the module. Thepiezoelectric device mounting member 405 is formed on the liquidcontainer mounting member 101 in the module 400 of the presentembodiment. The cylindrical part 403, which has a cylindrical shape, isformed on the base mount 102, which has a square shaped plan, the edgesof which are rounded, in the liquid container mounting member 401.Furthermore, the piezoelectric apparatus mounting member 405 includes aboard shaped element 405, which is set up on the cylindrical part 403,and a concave part 413. The actuator 106 is arranged on the concave part413 provided on the side face of the board shaped element 406. The topend of the board shaped element 406 is chamfered in predetermined angleso that the board shaped element is easy to fit into hole formed on theink cartridge when mounting the actuator 106 to ink cartridge.

FIG. 25 shows an exploded view of the module 400 shown in FIG. 24 toshow the structure of the module 400. As the module 100 shown in FIG.22, the module 400 includes a liquid container mounting member 401 and apiezoelectric device mounting member 405. The liquid container mountingmember 401 has the base mount 402 and the cylindrical part 403, and thepiezoelectric device mounting member 405 has the board shaped element406 and the concave part 413. The actuator 106 is connected to the plate410 and fixed to the concave part 413. The module 400 has a lead wire404 a and 404 b, actuator 106, and a film 408.

According to the present embodiment, the plate 410 is rectangular shape,and the opening 414 provided on the board shaped element 406 is formedin rectangular shape. The lead wire 404 a and 404 b, the actuator 106,the film 408, and the plate 410 can be attached to and removed from thebase mount 402. Each of the actuator 106, the film 408, and the plate410 is arranged symmetric with respect to the central axis which isextended to perpendicular direction to the plan of opening 414 and alsopass through the center of opening 414. Furthermore, each of the centersof the actuator 106, the film 408, and the plate 410 is arrangedsubstantially on the central axis of the opening 414.

The through hole 412 provided on the center of the plate 410 is formedsuch that the area of the through hole 412 is larger than the area ofthe opening of the cavity 162 of the actuator 106. The cavity 162 of theactuator 106 and the through hole 412 together forms ink storing part.The thickness of the plate 410 is preferably smaller than diameter ofthe through hole 412. For example, the thickness of the plate 410 issmaller than one third of the diameter of the through hole 412. Theshape of the through hole 412 is substantially true circle and symmetricwith respect to the central axis of the module 400. The shape of thecross-section of the periphery of the through hole 112 can be taperedshape or stepped shape. The module 400 can be mounted on the bottom ofthe container 1 such that the through hole 412 is arranged inside of thecontainer 1. Because the actuator 106 is arranged inside the container 1such that the actuator 106 extends in the vertical direction, thesetting of the timing of the ink end can be easily changed by changingthe height of the mounting position of the actuator 106 in the container1 by changing the height of the base mount 402.

FIG. 26 shows the further other embodiment of the module. As the module100 shown in FIG. 22, the module 500 of FIG. 26 includes a liquidcontainer mounting member 501 which has a base mount 502 and acylindrical part 503. Furthermore, the module 500 further has a leadwire 504 a and 504 b, actuator 106, a film 508, and a plate 510. Theopening 514 is formed on the center of the base mount 502, which isincluded in the liquid container mounting member 501, so that the basemount 502 can contain the lead wire 504 a and 504 b. The concave part513 is formed on the cylindrical part 503 so that the cylindrical part503 can contain the actuator 106, the film 508, and the plate 510. Theactuator 106 is fixed to the piezoelectric device mounting member 505through the plate 510. Therefore, the lead wire 504 a and 504 b, theactuator 106, the film 508, and the plate 510 are mounted on the liquidcontainer mounting member 501 as one body. The cylindrical part 503, thetop face of which is slanted in vertical direction, is formed on thebase mount which has a square shaped plan and the edges of which arerounded. The actuator 106 is arranged on the concave part 513 which isprovided on the top surface of the cylindrical part 503 that is slantedin vertical direction.

The top end of the module 500 is slanted, and the actuator 106 ismounted on this slanted surface. Therefore, if the module 500 is mountedon the bottom or the side of the container 1, the actuator 106 slants inthe vertical direction of the container 1. The slanting angle of the topend of the module 500 is substantially between 30 degree and 60 degreewith considering the detecting performance.

The module 500 is mounted on the bottom or the side of the container 1so that the actuator 106 can be arranged inside the container 1. Whenthe module 500 is mounted on the side of the container 1, the actuator106 is mounted on the container 1 such that the actuator 106 faces theupside, downside, or side of the container 1 with slanting. When themodule 500 is mounted on the bottom of the container 1, the actuator 106is preferable to be mounted on the container 1 such that the actuator106 faces to the ink supply port side of the container 1 with slanting.

FIG. 27 shows a cross-sectional view around the bottom of the container1 when the module 100 shown in FIG. 22 is mounted on the container 1.The module 100 is mounted on the container 1 so that the module 100penetrates through the side wall of the container 1. The O-ring 365 isprovided on the connection face of between the side wall of thecontainer 1 and the module 100 to seal between the module 100 and thecontainer 1. The module 100 is preferable to include the cylindricalpart as explained in FIG. 22 so that the module 100 can be sealed by theO-ring. By inserting the top end of the module 100 inside the container1, ink in the container 1 contacts with the actuator 106 through thethrough hole 112 of the plate 110. Because the resonant frequency of theresidual vibration of the actuator 106 is different depends on whetherthe circumference of the vibrating section of the actuator 106 is liquidor gas, the ink consumption status can be detected using the module 100.Furthermore, not only the module 100 can be mounted on the container 1and detect the existence of ink, but also the module 400 shown in FIG.24, module 500 shown in FIG. 26, or the module 700A and 700B shown inFIG. 28, and a mold structure 600 can be mounted on the container 1 anddetect the existence of the ink.

FIG. 28(A) shows the cross section of the ink container when mountingmodule 700B on the container 1. The present embodiment uses a module700B as an example of a mounting structure. The module 700B is mountedon the container 1 such that the liquid container mounting member 360protrude into the inside of the A through hole 370 is formed in themounting plate 350, and the through hole 370 faces to the vibratingsection of the actuator 106. Furthermore, a hole 382 is formed on thebottom wall of the module 700B, and a piezoelectric device mountingmember 363 is formed. The actuator 106 is arranged to close the one ofthe face of the hole 382. Therefore, ink contacts with the vibratingplate 176 through the hole 382 of the piezoelectric device mountingmember 363 and the through hole 370 of the mounting plate 350. The hole382 of the piezoelectric device mounting member 363 and the through hole370 of the mounting plate 350 together forms an ink storing part. Thepiezoelectric device mounting member 363 and the actuator 106 are fixedby the mounting plate 350 and the film material. The sealing structure372 is provided on the connection part of the liquid container mountingmember 360 and the container 1. The sealing structure 372 can be formedby the plastic material such as synthetic resin or O-ring. In FIG.28(A), the module 700B and the container 1 is separate body, however,the piezoelectric device mounting member can be constituted by a part ofthe container 1 as shown in FIG. 28(B).

The module 700B shown in FIG. 28 does not need to embed the lead wireinto the module as shown in FIG. 22 to FIG. 26. Therefore, the formingprocess becomes simple. Also, the exchange of the module 700B becomespossible so that the recycling of the module 700B also becomes possible.

There is possibility that the actuator 106 malfunctions by the contactof the ink which is dropped from a top face or a side face of thecontainer 1 with the actuator 106, the ink of which is attached to thetop face or the side face of the container 1 when the ink cartridge isshaken. However, because the liquid container mounting member 360 of themodule 700B protrudes into the inside of the container 1, the actuator106 does not malfunction by the ink dropped from the top face or theside face of the container 1.

Furthermore, the module 700B is mounted on the container 1 so that onlypart of the vibrating plate 176 and the mounting plate 350 are contactwith ink inside of the container 1 in the embodiment of FIG. 28(A). Theembedding of the electrode of the lead wire 104 a, 104 b, 404 a, 404 b,504 a, and 504 shown in FIG. 22 to FIG. 26 into the module becomesunnecessary for the embodiment shown in FIG. 28(A). Therefore, theforming process becomes simple. Also, the exchange of the actuator 106becomes possible so that the recycling of the actuator 106 also becomespossible.

FIG. 28(B) shows the cross section of the ink container when mountingactuator 106 on the container 1. A protecting member 361 is mounted onthe container separately with the actuator 106 in the ink cartridge ofthe embodiment shown in FIG. 28(B). Therefore, the protecting member 361and the actuator 106 is not one body as a module, and the protectingmember 361 thus can protect the actuator 106 not to be contact by theuser. A hole 380 which is provide on the front face of the actuator 106is arranged on the side wall of the container 1. The actuator 106includes the piezoelectric layer 160, the upper electrode 164, the lowerelectrode 166, the vibrating plate 176, and the mounting plate 350. Thevibrating plate 176is formed on the mounting plate 350, and the lowerelectrode 166 is formed on the vibrating plate 176. The piezoelectriclayer 160 is formed on the top face of the lower electrode 166, and theupper electrode 164 is formed on the top face of the piezoelectric layer160. Therefore, the main portion of the piezoelectric layer 160 isformed by sandwiching the main portion of the piezoelectric layer 160 bythe main portion of the upper electrode 164 and the lower electrode 166from top and bottom. The circular portion, which is a main portion ofeach of the piezoelectric layer 160, the upper electrode 164, and thelower electrode 166, forms a piezoelectric element. The piezoelectricelement is formed on the vibrating plate 176. The vibrating region ofthe piezoelectric element and the vibrating plate 176 constitutes thevibrating section, on which the actuator 106 actuary vibrates. A throughhole 370 is provided on the mounting plate 350. Furthermore, a hole 380is formed on the side wall of the container 1. Therefore, ink contactswith the vibrating plate 176 through the hole 380 of the container 1 andthe through hole 370 of the mounting plate 350. The hole 380 of thecontainer land the through hole 370 of the mounting plate 350 togetherforms ink storing part. Moreover, because the actuator 106 is protectedby the protecting member 361, the actuator 106 can be protected form theoutside contact. The base plate 178 shown in FIG. 1 can be used insteadof the mounting plate 350 in the embodiment shown in FIGS. 28(A) and(B).

FIG. 28(C) shows an embodiment that comprises a mold structure 600 whichincludes the actuator 106. In the present embodiment, a mold structure600 is used as one example of the mounting structure. The mold structure600 has the actuator 106 and a mold member 364. The actuator 106 and themold member 364 are formed in one body. The mold member 364 is formed bya plastic material such as silicon resin. The mold member 364 includes alead wire 362 in its inside. The mold member 364 is formed so that themold member 364 has two legs extended from the actuator 106. The end ofthe two legs of the mold member 364 are formed in a shape of hemisphereto liquid tightly fix the mold member 364 with container 1. The moldmember 364 is mounted on the container 1 such that the actuator 106protrudes into the inside of the container 1, and the vibrating sectionof the actuator 106 contacts with ink inside the container 1. The upperelectrode 164, the piezoelectric layer 160, and the lower electrode 166of the actuator 106 are protected from ink by the mold member 364.

Because the mold structure 600 shown in FIG. 28(C) does not need thesealing structure 372 between the mold member 364 and the container 1,the leaking of ink from the container 1 can be reduced. Moreover,because the mold structure 600 has a form that the mold structure 600does not protrude from the outside of the container 1, the moldstructure 600 can protect the actuator 106 from the outside contact.There is possibility that the actuator 106 malfunctions by the contactof the ink which is dropped from a top face or a side face of thecontainer 1 with the actuator 106, the ink of which is attached to thetop face or the side face of the container 1 when the ink cartridge isshaken. Because the mold member 364 of the mold structure 600 protrudesinto the inside of the container 1, the actuator 106 does notmalfunction by the ink dropped from the top face or the side face of thecontainer 1.

FIG. 29 shows an embodiment of ink cartridge and ink jet recordingapparatus which uses the actuator 106 shown in FIG. 1. A plurality ofink cartridges 180 is mounted on the ink jet recording apparatus whichhas a plurality of ink introducing members 182 and a holder 184 eachcorresponding to the each of ink cartridge 180, respectively. Each ofthe plurality of ink cartridges 180 contains different types of ink, forexample, different color of ink. The actuator 106, which detects atleast acoustic impedance, is mounted on the each of bottom of theplurality of ink cartridge 180. The residual quantity of ink in the inkcartridge 180 can be detected by mounting the actuator 106 on the inkcartridge 180.

FIG. 30 shows a detail around the head member of the ink jet recordingapparatus. The ink jet recording apparatus has an ink introducing member182, a holder 184, a head plate 186, and a nozzle plate 188. A pluralityof nozzle 190, which jet out ink, is formed on the nozzle plate 188. Theink introducing member 182 has an air supply hole 181 and an inkintroducing inlet 183. The air supply hole 181 supplies air to the inkcartridge 180. The ink introducing inlet 183 introduces ink from the inkcartridge 180. The ink cartridge 180 has an air introducing inlet 185and an ink supply port 187. The air introducing inlet 185 introduces airfrom the air supply hole 181 of the ink introducing member 182. The inksupply port 187 supplies ink to the ink introducing inlet 183 of the inkintroducing member 182. By introducing air from the ink introducingmember 182 to the ink cartridge 180, the ink cartridge 180 acceleratesthe supply of ink from the ink cartridge 180 to the ink introducingmember 182. The holder 184 communicates ink supplied from the inkcartridge 180 through the ink introducing member 182 to the head plate186.

FIG. 31 shows other embodiment of the ink cartridge 180 shown in FIG.30. The actuator 106 is mounted on the bottom face 194 a, which isformed to be slanted in vertical direction, of the ink cartridge 180Ashown in the FIG. 31(A). A wave preventing wall 192 is provided on theposition where has the predetermined height from the bottom face of theinside the ink container 194 and also faces to the actuator 106 insidethe ink container 194 of the ink cartridge 180. Because the actuator 106is mounted on the ink container 194 slanted in vertical direction, thedrainage of ink can be improved.

A gap, which is filled with ink, is formed between the actuator 106 andthe wave preventing wall 192. The space between the wave preventing wall192 and the actuator 106 has a space such that the space does not holdink by capillary force. When the ink container 194 is rolled, ink waveis generated inside the ink container 194 by the rolling, and there ispossibility that the actuator 106 malfunctions by detecting gas or anair bubble caused by the shock of the ink wave. By providing the wavepreventing wall 192, ink wave around the actuator 106 can be preventedso that the malfunction of the actuator 106 can be prevented.

The actuator 106 of the ink cartridge 180B shown in FIG. 31 is mountedon the sidewall of the supply port of the ink container 194. Theactuator 106 can be mounted on the side wall or bottom face of the inkcontainer 194 if the actuator 106 is mounted nearby the ink supply port187. The actuator 106 is preferably mounted on the center of the widthdirection of the ink container 194. Because ink is supplied to theoutside through the ink supply port 187, ink and actuator 106 reliablycontacts until the timing of the ink near end by providing the actuator106 nearby the ink supply port 187. Therefore, the actuator 106 canreliably detect the timing of the ink near end.

Furthermore, by providing the actuator 106 nearby the ink supply port187, the setting position of the actuator 106 to the connection point onthe carriage on the ink container becomes reliable during the mountingof the ink container on the cartridge holder of the carriage. It isbecause the reliability of coupling between the ink supply port with theink supply needle is most important during the coupling of the inkcontainer and the carriage. If there is even a small gap, the tip of theink supply needle will be hurt or a sealing structure such as O-ringwill be damaged so that the ink will be leaked. To prevent this kind ofproblems, the ink jet printer usually has a special structure that canaccurately positioning the ink container during the mounting of the inkcontainer on the carriage. Therefore, the positioning of the actuator106 becomes reliable by arranging the actuator nearby the ink supplyport. Furthermore, the actuator 106 can be further reliably positionedby mounting the actuator 106at the center of the width direction of theink container 194. It is because the rolling is the smallest when theink container rolls along an axis, the center of which is center line ofthe width direction, during the mounting of the ink container on theholder.

FIG. 32 shows further other embodiment of the ink cartridge 180. FIG.32(A) shows a cross section of an ink cartridge 180C, and FIG. 32(B)shows a cross section which enlarges the side wall 194 b of an inkcartridge 180C shown in FIG. 32(A). FIG. 32(C) shows perspective viewfrom the front of the side wall 194 b of the ink cartridge 180C. Thesemiconductor memory device 7 and the actuator 106 are formed on thesame circuit board 610 in the ink cartridge 180C. As shown in FIGS.32(B) and (C), the semiconductor memory device 7 is formed on the upperside of the circuit board 610, and the actuator 106 is formed on thelower side of the semiconductor memory device 7 on the same circuitboard 610. A different-type O-ring 614 is mounted on the side wall 194bsuch that the different-type O-ring 614 surrounds the actuator 106. Aplurality of caulking part 616 is formed on the side wall 194 b tocouple the circuit board 610 with the ink container 194. By coupling thecircuit board 610 with the ink container 194 using the caulking part 616and pushing the different-type O-ring 614 to the circuit board 610, thevibrating region of the actuator 106 can contacts with ink, and at thesame time, the inside of the ink cartridge is sealed from outside of theink cartridge.

A terminals 612 are formed on the semiconductor memory device 7 andaround the semiconductor memory device 7. The terminal 612 transfer thesignal between the semiconductor memory device 7 and outside the inkjetrecording apparatus. The semiconductor memory device 7 can beconstituted by the semiconductor memory which can be rewritten such asEEPROM. Because the semiconductor memory device 7 and the actuator 106are formed on the same circuit board 610, the mounting process can befinished at one time during mounting the semiconductor memory device 7and the actuator 106 on the ink cartridge 180C. Moreover, the workingprocess during the manufacturing of the ink cartridge 180C and therecycling of the ink cartridge 180C can be simplified. Furthermore, themanufacturing cost of the ink cartridge 180C can be reduced because thenumbers of the parts can be reduced.

The actuator 106 detects the ink consumption status inside the inkcontainer 194. The semiconductor memory device 7 stores the informationof ink such as residual quantity of ink detected by the actuator 106.That is, the semiconductor memory device 7 stores the informationrelated to the characteristic parameter such as the characteristic ofink and the ink cartridge used for the actuator 106 when detecting theink consumption status. The semiconductor memory device 7 previouslystores the resonant frequency of when ink inside the ink container 194is full, that is, when ink is filled in the ink container 194sufficiently, or when ink in the ink container 194 is end, that is, inkin the ink container 194 is consumed, as one of the characteristicparameter. The resonant frequency when the ink inside the ink container194 is full status or end status can be stored when the ink container ismounted on the ink jet recording apparatus for the first time. Moreover,the resonant frequency when the ink inside the ink container 194 is fullstatus or end status can be stored during the manufacturing of the inkcontainer 194. Because the unevenness of the detection of the residualquantity of ink can be corrected by storing the resonant frequency whenthe ink inside the ink container 194 is full status or end status in thesemiconductor memory device 7 previously and reading out the data of theresonant frequency at the ink jet recording apparatus side, it can beaccurately detected that the residual quantity of ink is decreased tothe reference value.

FIG. 33 shows further other embodiment of the ink cartridge 180. Aplurality of actuators 106 is mounted on the side wall 194 b of the inkcontainer 194 in the ink cartridge 180D shown in FIG. 33(A). It ispreferable to use the plurality of the actuators 106 which is formed inone body as shown in FIG. 14 for these plurality of actuators 106. Theplurality of actuators 106 is arranged on the side wall 194 b withinterval in vertical direction. By arranging the plurality of actuators106 on the side wall 194 b with interval in vertical direction, theresidual quantity of ink can be detected step by step.

The ink cartridge 180E shown in FIG. 33(B) mounts a actuator 606 whichis long in vertical direction on the side wall 194 b of the inkcontainer 194. The change of the residual quantity of ink inside the inkcontainer 194 can be detected continuously by the actuator 606 which islong in vertical direction. The length of the actuator 606 is preferablylonger than the half of the height of the side wall 194b. In FIG. 33(B),the actuator 606 has the length from the substantially from the top endto the bottom end of the side wall 194 b.

The ink cartridge 180F shown in FIG. 33(C) mounts a plurality ofactuators 106 on the side wall 194 b of the ink container 194 as the inkcartridge 180D shown in FIG. 33(A). The ink cartridge 18OF furthercomprises the wave preventing wall 192, which is long in verticaldirection, along the side wall 194 b with predetermined space with theside wall 194 b such that the wave preventing wall 192 faces directly tothe plurality of actuators 106. It is preferable to use the plurality ofthe actuators 106 which is formed in one body as shown in FIG. 14 forthese plurality of actuators 106. A gap which is filled with ink isformed between the actuator 106 and the wave preventing wall 192.Moreover, the gap between the wave preventing wall 192 and the actuator106 has a space such that the gap does not hold ink by capillary force.When the ink container 194 is rolled, ink wave is generated inside theink container 194 by the rolling, and there is possibility that theactuator 106 malfunctions by detecting gas or an air bubble caused bythe shock of the ink wave. By providing the wave preventing wall 192,ink wave around the actuator 106 can be prevented so that themalfunction of the actuator 106 can be prevented. The wave preventingwall 192 also prevents the air bubble generated by the rolling of ink toenter to the actuator 106.

FIG. 34 shows further other embodiment of the ink cartridge 180. The inkcartridge 180G shown in FIG. 34(A) has a plurality of partition walls212, each of which extends downward from the top face 194 c of the inkcontainer 194. Because each of lower end of the partition walls 212 andthe bottom face of the ink container 194 has a predetermined gap, thebottom part of the ink container 194 communicates with each other. Theink cartridge 180G has a plurality of containing chambers 213 divided bythe each of plurality of partition walls 212. The bottom part of theplurality of the containing chambers 213 communicates with each other.In each of the plurality of the containing chamber 213, the actuator 106is mounted on the top face 194 c of the ink container 194. It ispreferable to use the plurality of the actuators 106 which is formed inone body as shown in FIG. 14 for these plurality of actuators 106. Theactuator 106 is arranged on substantially center of the top face 194 cof the containing chamber 213 of the ink container 194. The volume ofthe containing chamber 213 is arranged such that the volume of thecontaining chamber 213 of the ink supply port 187 is the largest, andthe volume of the containing chamber 213 gradually decreases as thedistance from the ink supply port 187 increases to the inner part of theink cartridge 180G. Therefore, the space between each of the actuator106 is widest at the ink supply port 187 side and becomes narrower asthe distance from the ink supply port 187 increases to the inner part ofthe ink cartridge 180G. Because ink is drained from the ink supply port187, and air enters from the air introducing inlet 185, ink is consumedfrom the containing chamber 213 of the ink supply port 187 side to thecontaining chamber 213 of the inner part of the ink cartridge 180G. Forexample, the ink in the containing chamber 213 which is most near to theink supply port 187 is consumed, and during the ink level of thecontaining chamber 213 which is most near to the ink supply port 187decreases, the other containing chamber 213 are filled with ink. Whenthe ink in the containing chamber 213 which is most near to the inksupply port 187 is consumed totally, air enters to the containingchamber 213 which is second by counted from the ink supply port 187,then the ink in the second containing chamber 213 is beginning to beconsumed so that the ink level of the second containing chamber 213begin to decrease. At this time, ink is filled in the containing chamber213 which is third or more than third by counted from the ink supplyport 187. In this way, ink is consumed from the containing chamber 213which is most near to the ink supply port 187 to the containing chamber213 which is far from the ink supply port 187 in order.

As shown above, because the actuator 106 is arranged on the top face 194c of the ink container 194 with interval for each of the containingchamber 213, the actuator 106 can detect the decrease of the inkquantity step by step. Furthermore, because the volume of the containingchamber 213 decreases from the ink supply port 187 to the inner part ofthe containing chamber 213 gradually, the time interval when theactuator 106 detects the decrease of the ink quantity graduallydecreases. Therefore, the frequency of the ink quantity detection can beincreased as the ink end is drawing near.

The ink cartridge 180H shown in FIG. 34(B) has one partition wall 212which extends downward from the top face 194 c of the ink container 194.Because lower end of the partition walls 212 and the bottom face of theink container 194 have a predetermined space, the bottom part of the inkcontainer 194 communicates with each other. The ink cartridge 180H hastwo containing chambers 213 a and 213 b divided by the partition wall212. The bottom part of the containing chambers 213 a and 213 bcommunicates with each other. The volume of the containing chamber 213 aof the ink supply port 187 side is larger than the volume of thecontaining chamber 213 b which is located in a inner part of the inkcartridge 180H far from the ink supply port 187. The volume of thecontaining chamber 213 b is preferably smaller than the half of thevolume of the containing chamber 213 a.

The actuator 106 is mounted on the top face 194 c of the containingchamber 213B. Furthermore, a buffer 214, that is a groove for catchingthe air bubble which enters to the ink cartridge 180H duringmanufacturing of the ink cartridge 180H, is formed on the containingchamber 213 b. In FIG. 34(B), the buffer 214 is formed as a grooveextended upward from the side wall 194 b of the ink container 194.Because the buffer 214 catches the air bubble enters inside thecontaining chamber 213 b, the malfunction of the actuator 106 bydetecting an ink end when catching the air bubble can be prevented.Furthermore, by providing actuator 106 on the top face 194 c of thecontaining chamber 213 b, ink can be completely consumed by correctingthe ink quantity, which is measured from the detection of the ink enduntil the complete consumption of ink, with the corresponding inkconsumption status of the containing chamber 213 a calculated from thedot counter. Furthermore, by adjusting the volume of the containingchamber 213 b by changing the length or the interval of the partitionwall 212, the ink quantity which can be consumed after the detection ofthe ink end can be changed.

The ink cartridge 180I shown in FIG. 34(C) fills a porous member 216 inthe containing chamber 213 b of the ink cartridge 180H shown in FIG.34(B). The porous member 216 is filled inside the containing chamber 213b from the top face to the bottom face of the porous member 216 b. Theporous member 216 contacts with the actuator 106. There is a possibilitythat the actuator 106 malfunctions by the entering of the air bubbleinside the containing chamber 213 b when the ink container fall down orwhen the containing chamber 213 b moves back and forth with thecarriage. If the porous member 216 is provided on the containing chamber213 b, the porous member 216 captures air to prevent entering of airinto the actuator 106. Furthermore, because the porous member 216 holdsink, the porous member 216 can prevent the actuator 106 to malfunctionas detecting the ink end status as ink exist status which is caused byattaching of the ink on the actuator 106 when the ink container shakes.The porous member 216 is preferable to be provided in the containingchamber 213 having a smallest volume. Furthermore, by providing actuator106 on the top face 194 c of the containing chamber 213 b, ink can beconsumed to the end by correcting the ink quantity which is measuredfrom the detection of the ink end until the complete consumption of ink.Furthermore, The ink quantity which can be consumed after the detectionof the ink near end can be changed by adjusting the volume of thecontaining chamber 213 b by changing the length and interval of thepartition wall 212.

FIG. 34(D) shows an ink cartridge 180J, the porous member 216 of whichis constituted by two kinds of porous members 216A and 216B having adifferent hole diameter with each other. The porous member 216A islocated on the upper side of the porous member 216B. The hole diameterof the porous member 216A which is located on the upper side of thecontaining chamber 213 b is larger than the hole diameter of the porousmember 216B which is located on the lower side of the containing chamber213B. The porous member 216A can be formed by the member which has alower affinity for liquid than the affinity for liquid of the memberwhich forms the porous member 216B. Because the capillary force of theporous member 216B, which has small hole diameter, is larger than thecapillary force of the porous member 216A, which has large holediameter, the ink in the containing chamber 213 b is collected to theporous member 216B located on the lower side of the containing chamber213B and held by the porous member 216B. Therefore, once the air reachesto the actuator 106, and the actuator 106 detects the non-ink status,ink does not reaches to the actuator 106 again so that the actuator 106does not malfunction to detect the ink exist status. Furthermore,because the porous member 216B which is far from the actuator 106absorbs ink, the drainage of ink around the actuator 106 improves, andthe quantity of change of the acoustic impedance during the detection ofthe ink existence increases. Moreover, by providing the actuator 106 onthe top face 194 c of the containing chamber 213 b, ink can be consumedto the end by correcting the ink quantity which is measured from thedetection of the ink near end until the complete consumption of ink.Furthermore, The ink quantity which can be consumed after the detectionof the ink near end can be changed by adjusting the volume of thecontaining chamber 213 b by changing the length and interval of thepartition wall 212.

FIG. 35 shows a cross section of an ink cartridge 180K which is furtherother embodiment of the ink cartridge 180I shown in FIG. 34(C). Theporous member 216 in the ink cartridge 180K shown in FIG. 35 is designedsuch that the area of the cross section on the horizontal plane of thelower part of the porous member 216 is compressed to be decreasesgradually to the direction to the bottom face of the ink container 194.Therefore, the hole diameter of the porous member 216 decreasesgradually to the direction to the bottom face of the ink container 194.Ink cartridge 180K shown in FIG. 35(A) has a rib which is provided onthe side wall of the ink container 194 to compress the lower part of theporous member 216 to reduce the hole diameter of the lower part of theporous member 216. Because the hole diameter of the lower part of theporous member 216 reduced by the compression, ink is collected and heldby the lower part of the porous member 216. Because the lower part ofthe porous member 216 which is far from the actuator 106 absorbs ink,the drainage of ink around the actuator 106 improves, and the quantityof change of the acoustic impedance during the detection of the inkexistence increases. Therefore, the error, of which the actuator 106detects the non ink status as the ink exist status by the attaching ofink on the actuator 106 mounted on the top face of the ink cartridge180K by rolling of ink, can be prevented.

In the ink cartridge 180L shown in FIG. 35(B) and FIG. 35(C), tocompress to decrease the area of the cross section on the horizontalplane of the lower part of the porous member 216 gradually to thedirection to the bottom face of the ink container 194, the area of thecross section on the horizontal plane of the containing chambergradually decreases to the direction to the bottom face of the inkcontainer 194. Because the hole diameter of the lower part of the porousmember 216 reduced by the compression, ink is collected and held by thelower part of the porous member 216. Because the lower part of theporous member 216B which is far from the actuator 106 absorbs ink, thedrainage of ink around the actuator 106 improves, and the quantity ofchange of the acoustic impedance during the detection of the inkexistence increases. Therefore, the error, of which the actuator 106detects the non ink status as the ink exist status by the attaching ofink on the actuator 106 mounted on the top face of the ink cartridge180L by rolling of ink, can be prevented.

FIG. 36 shows other embodiment of the ink cartridge using the actuator106. The ink cartridge 220A shown in FIG. 36(A) has a first partitionwall 222 provided such that it extends downward from the top face of theink cartridge 220A. Because there is a predetermined space between thelower end of the first partition wall 222 and the bottom face of the inkcartridge 220A, ink can flows into the ink supply port 230 through thebottom face of the ink cartridge 220A. A second partition wall 224 isformed such that the second partition wall 224 extends upward from thebottom face of the ink cartridge 220A on the more ink supply port 230side of the first partition wall 222. Because there is a predeterminedspace between the upper end of the second partition wall 224 and the topface of the ink cartridge 220A, ink can flows into the ink supply port230 through the top face of the ink cartridge 220A.

A first containing chamber 225 a is formed on the inner part of thefirst partition wall 222, seen from the ink supply port 230, by thefirst partition wall 222. On the other hand, a second containing chamber225 b is formed on the front side of the second partition wall 224, seenfrom the ink supply port 230, by the second partition wall 224. Thevolume of the first containing chamber 225 a is larger than the volumeof the second containing chamber 225 b. A capillary passage 227 isformed by providing a space, which can generate the capillaryphenomenon, between the first partition wall 222 and the secondpartition wall 224. Therefore, the ink in the first containing chamber225 a is collected to the capillary passage 227 by the capillary forceof the capillary passage 227. Therefore, the capillary passage 227 canprevent that the air or air bubble enters into the second containingchamber 225 b. Furthermore, the ink level in the second containingchamber 225 b can decrease steadily and gradually. Because the firstcontaining chamber 225 a is formed at more inner part of the secondcontaining chamber 225 b, seen from the ink supply port 230, the ink inthe second containing chamber 225 b is consumed after the ink in thefirst containing chamber 225 a is consumed.

The actuator 106 is mounted on the side wall of the ink cartridge 220Aof the ink supply port 230 side, that is, the side wall of the secondcontaining chamber 225 b of the ink supply port 230 side. The actuator106 detects the ink consumption status inside the second containingchamber 225 b. The residual quantity of ink at the timing closed to theink near end can be detected stably by mounting the actuator 106 on theside wall of the second containing chamber 225 b. Furthermore, bychanging the height of the mounting position of the actuator 106 on theside wall of the second containing chamber 225 b, the timing todetermine which ink residual quantity as an ink end can be freely set.Because ink is sullied from the first containing chamber 225 a to thesecond containing chamber 225 b by the capillary passage 227, theactuator 106 does not influenced by the rolling of ink caused by therolling of the ink cartridge 220A, and actuator 106 can thus reliablymeasure the ink residual quantity. Furthermore, because the capillarypassage 227 holds ink, the capillary passage 227 can prevent ink to flowbackward from the second containing chamber 225 b to the firstcontaining chamber 225 a.

A check valve 228 is provided on the top face of the ink cartridge 220A.The leaking of ink outside of the ink cartridge 220A caused by therolling of the ink cartridge 220A can be prevented by the check valve228. Furthermore, the evaporation of ink from the ink cartridge 220A canbe prevented by providing the check valve 228 on the top face of the inkcartridge 220A. If ink in the ink cartridge 220A is consumed, andnegative pressure inside the ink cartridge 220A exceeds the pressure ofthe check valve 228, the check valve 228 opens and introduces air intothe ink cartridge 220A. Then the check valve 228 closes to maintain thepressure inside the ink cartridge 220A to be stable.

FIGS. 36(C) and (D) shows a detailed cross-section of the check valve228. The check valve 228 shown in FIG. 36(C) has a valve 232 whichincludes flange 232 a formed by rubber. An airhole 233, whichcommunicates air between inside and outside of the ink cartridge 220, isprovided on the ink cartridge 220 such that the airhole 233 faces to theflange 232 a. The airhole 233 is opened and closed by the flange 232 a.The check valve 228 opens the flange 232 a inward the ink cartridge 220when the negative pressure in the ink cartridge 220 exceeds the pressureof the check valve 228 by the decrease of ink inside the ink cartridge220A, and thus the air outside the ink cartridge 220 is introduced intothe ink cartridge 220. The check valve 228 shown in FIG. 36(D) has avalve 232 formed by rubber and a spring 235. If the negative pressureinside the ink cartridge 220 exceeds the pressure of the check valve228, the valve 232 presses and opens the spring 235 to introduce theoutside air into the ink cartridge 220 and then closes to maintain thenegative pressure inside the ink cartridge 220 to be stable.

The ink cartridge 220B shown in FIG. 36(B) has a porous member 242 inthe first containing chamber 225 a instead of providing the check valve228 on the ink cartridge 220A as shown in FIG. 36. The porous member 242holds the ink inside the ink cartridge 220B and also prevents ink to beleaked outside of the ink cartridge 220B during the rolling of the inkcartridge 220B.

The embodiment that the actuator 106 is mounted on an ink cartridge or acarriage, in which the ink cartridge is a separate body with thecarriage and mounted on the carriage, has been explained above. However,the actuator 106 can be mounted on the ink tank which is mounted on theinkjet recording apparatus together with a carriage and formed togetherwith a carriage as one body. Furthermore, the actuator 106 can bemounted on the ink tank of the off-carriage type. The off-carriage typeink tank is a separate body with a carriage and supplies ink to carriagethrough such as tube. Moreover, the actuator of the present embodimentcan be mounted on the ink cartridge 180 constituted so that a recordinghead and an ink container are formed as one body and possible to beexchanged.

Although the present invention has been described by way of exemplaryembodiments, it should be understood that many changes and substitutionsmay be made by those skilled in the art without departing from thespirit and the scope of the present invention which is defined only bythe appended claims.

The liquid consumption status detecting method and liquid container ofthe present invention can detect the residual quantity of liquidaccurately and also do not need the complicated sealing structure.Furthermore, the liquid consumption status detection method of thepresent invention does not to be influenced by the unstable measuringsignal generated at the early stage of the measuring of the liquidconsumption status. Furthermore, the liquid consumption status detectionmethod of the present invention can reduce the time for detecting theliquid consumption status.

1. A detection control circuit for detecting a consumption status ofliquid contained in a liquid container by a detection device having apiezoelectric element, the detection device comprising an actuallyvibrating part facing a cavity which defines the vibration of theliquid, the circuit comprising: a measurement circuit segment formeasuring a residual vibration of the detection device; and a detectioncircuit segment receiving a signal from said measurement circuit segmentand outputting a signal indicative of the consumption status of theliquid contained in the liquid container on the basis of the outputsignal of said measurement circuit segment.
 2. The detection controlcircuit according to claim 1, wherein said measurement circuit segmentmeasures a frequency of the residual vibration of the detection device.3. The detection control circuit according to claim 1, wherein saidmeasurement circuit segment measures at least one resonance frequency ofthe liquid surrounding the detection device.
 4. The detection controlcircuit according to claim 1, wherein said measurement circuit segmentcomprises an amplifier, said amplifier comprises a PNP type transistorand a NPN type transistor which complementarily connecting with said PNPtype transistor, and emitter of said PNP type transistor and an emitterof said NPN type transistor connect with each other.
 5. The detectioncontrol circuit according to claim 4, wherein a drive voltage generatedbetween a point connecting between the emitter of said NPN typetransistor and said PNP type transistor and the ground is applied to thedetection device.
 6. The detection control circuit according to claim 1,wherein said measurement circuit segment comprises an amplifier, saidamplifier comprises a P-channel field effect transistor and a N-channelfield effect transistor which complementarily connecting with saidP-channel field effect transistor, and a source of said P-channeltransistor and a source of said N-channel transistor connect with eachother.
 7. The detection control circuit according to claim 6, wherein adrive voltage generated between a point connecting between the sourcesof said N-channel FET and said P-channel FET and the ground is appliedto the detection device.
 8. The detection control circuit according toclaim 1, wherein the liquid container is an ink cartridge for an ink-jettype printing apparatus.
 9. The detection control circuit according toclaim 1, wherein a node of the vibration of the detection device islocated on the periphery of the cavity.
 10. The detection controlcircuit according to claim 1, wherein at least a part of said vibratingpart contacts the liquid in the liquid container.
 11. The detectioncontrol circuit according to claim 1, wherein the depth of said cavityis smaller than the narrowest width of said cavity.
 12. The detectioncontrol circuit according to claim 11, wherein a ratio of a radius ofsaid cavity with a depth thereof is larger than 3π/8.
 13. The detectioncontrol circuit according to claim 11, wherein the depth of said cavityis less than one-third of the narrowest width of said cavity.
 14. Thedetection control circuit according to claim 1, wherein said detectiondevice comprises a base member at which said cavity is formed, and thecompliance of said vibrating part is greater than that of said basemember.